JP2013112593A - Apparatus and method for producing polycrystalline silicon ingot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for producing a polycrystalline silicon ingot, capable of producing a high-quality, large-sized polycrystalline silicon ingot with few SiC impurities.SOLUTION: The apparatus for producing the polycrystalline silicon ingot includes: a crucible having an upper opening, a heating unit that is installed in an outer periphery of the crucible and heats and melts a silicon raw material housed inside the crucible; a transfer mechanism that vertically moves the crucible relatively to the heating unit; a cover that has an inert gas inlet and covers the upper opening of the crucible in an openable manner; and an inert gas inlet tube that introduces an inert gas into the inert gas inlet.

Description

  The present invention relates to a polycrystalline silicon ingot suitably used for a solar cell, an apparatus for manufacturing the same, a method for manufacturing the same, and an application thereof.

  Recently, renewable energy has attracted attention for environmental problems on a global scale. Among them, solar cells are attracting a great deal of attention. There are several types of solar cells, including bulk, thin film, and dye sensitization. Among them, polycrystalline silicon solar cells using polycrystalline silicon wafers have the highest cost performance and the largest market. Accounted for. Therefore, in order to promote further spread of polycrystalline silicon solar cells, there is a demand for lowering the cost of polycrystalline silicon solar cells.

As a silicon crystal solar cell, an n-type layer is formed by a method such as diffusion on the surface of a p-type silicon substrate to which a small amount of a group III element such as B (boron) or Ga (gallium) is added. A pn junction type having a pn junction is most common. In addition, a p-type layer is formed on the surface of an n-type silicon substrate to which a small amount of a group V element such as P (phosphorus) is added, or an n- or p-type layer is grown on a p- or n-substrate by thin film growth. There are silicon crystal solar cells having various structures such as those having a structure in which n ⁺ and p ⁺ regions are formed on the back side of an n-type silicon substrate and electrodes are collected on the back side.

Polycrystalline silicon used for solar cells can be obtained by manufacturing a silicon ribbon or spherical silicon, but is generally manufactured by a manufacturing method called a casting method. In the casting method, for example, a silicon melt is held in a crucible made of silica, and then the silicon melt is unidirectionally solidified from the bottom side of the crucible to the liquid surface side to produce a polycrystalline silicon ingot. Thereafter, in general, the polycrystalline silicon ingot is processed into a prismatic block of an appropriate size by a band saw, and the block is sliced by a wire saw to obtain a wafer. A polycrystalline silicon solar cell is manufactured using the polycrystalline silicon wafer thus obtained, and a solar cell module is manufactured by modularizing a plurality of solar cells.
Here, in the following description of the present specification, the concept including “solar battery cell” and “solar battery module” is simply referred to as “solar battery”. Therefore, for example, what is described as “polycrystalline silicon solar cell” is meant to include “polycrystalline silicon solar cell” and “polycrystalline silicon solar cell module”.

  Silicon carbide foreign matter (SiC foreign matter) present in the polycrystalline silicon ingot causes various processing defects during block processing and block slicing of the polycrystalline silicon ingot. Since SiC is harder than silicon, the wire saw breaks during slicing. Alternatively, a defective wafer is generated due to a problem such as a step in the wafer or an increase in the in-plane thickness distribution of the wafer. Further, in order to prevent the wire saw from being disconnected in the slicing step, when SiC foreign matter is confirmed on the block surface, it is necessary to excise a portion where the SiC foreign matter has been confirmed in advance, but this significantly reduces the yield.

Further, also in the manufacturing process of the solar battery cell, if SiC foreign matter is present in the polycrystalline silicon wafer, a characteristic defect called Id defect is caused and yield is lowered. Here, the Id defect is defined as a defect in which the reverse current that flows when an appropriate reverse voltage is applied to the solar cell in the non-irradiation state exceeds the reference value. The reference value of the reverse voltage or reverse current to be applied is determined by the structure of the solar cell module, the number of solar cells in series, etc., when some of the solar cells connected in series are shaded, etc. It is determined for the purpose of suppressing the heat generation at.
In order to reduce the cost of the polycrystalline silicon solar cell, it is necessary to avoid the above-described reduction in processing yield and reduction in the characteristic yield of the solar cell. To that end, SiC foreign matter in the polycrystalline silicon ingot is required. Need to be reduced.

  The cause of the generation of SiC foreign matter is considered to be that carbon impurities are originally contained in the silicon raw material, and that carbon impurities are mixed into the silicon melt during casting. Even when a polysilicon raw material having a low carbon concentration is used, SiC foreign matter is generated in the ingot. Therefore, it is essential to reduce carbon impurities mixed during casting. As a mixing route of carbon impurities at the time of casting, SiO evaporated from the silicon melt (molten metal) reacts with a graphite member (for example, a graphite heating part, a carbon-based heat insulating material, etc.) that has become a high temperature in the furnace, and CO. A route is considered in which gas is generated and the CO gas is taken into the silicon melt.

  As a polycrystalline silicon ingot manufacturing apparatus for reducing the carbon impurity concentration, a crucible, an upper heating unit and a lower heating unit disposed above and below the crucible, and a gas for supplying an inert gas toward the silicon melt And a plate-like lid provided between the silicon melt and the upper heating part, and a through hole for inserting the gas pipe is formed near the center of the lid, and a gas is formed at the peripheral part of the lid. An apparatus in which a passage gap is formed has been proposed (for example, see Patent Document 1).

Japanese Patent No. 4099884

In general, in order to obtain a high-output solar cell, a high-quality polycrystalline silicon ingot is manufactured and widely used by unidirectionally solidifying a silicon melt.
However, the polycrystalline silicon ingot production apparatus described in Patent Document 1 has a low degree of freedom for optimizing crystal growth conditions, and cannot produce a high-quality polycrystalline silicon ingot. In addition, since the lid is fixed at the height of the upper opening of the crucible, there is a problem that the amount of silicon raw material charged into the crucible is limited.

  The present invention has been made in view of the above-described problems, and mainly provides a polycrystalline silicon ingot manufacturing apparatus that can manufacture a high-quality and large-sized polycrystalline silicon ingot with few SiC foreign substances. Objective.

  Thus, according to the present invention, the crucible having the upper opening, the heating unit that is provided on the outer periphery of the crucible and heats and melts the silicon raw material stored in the crucible, and the crucible and the heating unit are relatively A vertical movement mechanism, a cover having an inert gas introduction hole and covering the upper opening of the crucible so as to be openable and closable, and introducing an inert gas into the inert gas introduction hole An apparatus for producing a polycrystalline silicon ingot comprising a tube is provided.

  Further, according to another aspect of the present invention, there is provided a polycrystalline silicon ingot manufacturing method in which a polycrystalline silicon ingot is grown while introducing an inert gas using the above-described polycrystalline silicon ingot manufacturing apparatus.

According to still another aspect of the present invention, a polycrystalline silicon ingot produced by the polycrystalline silicon ingot producing method, a polycrystalline silicon block obtained by processing the polycrystalline silicon ingot, and the polycrystalline silicon A polycrystalline silicon wafer obtained by processing a block and a polycrystalline silicon solar cell manufactured using the polycrystalline silicon wafer are provided.
Here, in this specification, the concept including “silicon block” and “silicon wafer” is referred to as “silicon material”. Thus, for example, what is described as “polycrystalline silicon material” is meant to include “polycrystalline silicon block” and “polycrystalline silicon wafer”.

  According to the polycrystalline silicon ingot producing apparatus of the present invention, it is possible to produce a polycrystalline silicon ingot with few SiC foreign substances at low cost. As a result, it is possible to reduce the cost of silicon materials and solar cells manufactured from polycrystalline silicon ingots, and the spread of polycrystalline silicon solar cells can be accelerated.

It is sectional drawing which shows the time of the raw material fusion | melting in Embodiment 1 of the polycrystalline-silicon ingot manufacturing apparatus of this invention. It is sectional drawing which shows the time of completion of solidification in the polycrystalline silicon ingot manufacturing apparatus of Embodiment 1. FIG. 3 is a perspective view showing a crucible in the polycrystalline silicon ingot manufacturing apparatus of Embodiment 1. It is a front view which shows the 1st board | plate material of the cover in the polycrystalline silicon ingot manufacturing apparatus of Embodiment 1. FIG. It is a front view which shows the 2nd board | plate material of the cover in the polycrystalline silicon ingot manufacturing apparatus of Embodiment 1. FIG. It is a perspective view which shows the cover body of the cover in the polycrystalline silicon ingot manufacturing apparatus of Embodiment 1. FIG. FIG. 3 is a perspective view showing a part of a cover and an inert gas introduction pipe in the polycrystalline silicon ingot manufacturing apparatus of the first embodiment. It is a partial expanded sectional view which shows the inert gas introducing | transducing part in Embodiment 2 of the polycrystalline-silicon ingot manufacturing apparatus of this invention. It is sectional drawing which shows the time of the raw material fusion | melting in Embodiment 3 of the polycrystalline-silicon ingot manufacturing apparatus of this invention. It is sectional drawing which shows the time of the completion of solidification in the polycrystalline silicon ingot manufacturing apparatus of Embodiment 3. 1 is a first diagram illustrating a solar cell forming step in Example 1. FIG. FIG. 3 is a second diagram showing a solar battery cell forming step in Example 1. FIG. 5 is a third diagram illustrating a solar cell formation step in Example 1. FIG. 6 is a fourth diagram showing a solar cell formation step in Example 1. FIG. 10 is a fifth diagram illustrating a solar cell formation step in Example 1; FIG. 10 is a sixth diagram illustrating a solar cell formation step in Example 1. FIG. 10 is a seventh diagram illustrating a solar battery cell formation step in Example 1; It is an 8th figure which shows the photovoltaic cell formation process in Example 1. FIG. FIG. 10 is a ninth diagram illustrating the solar cell formation step in Example 1. 2 is a partial cross-sectional view showing a polycrystalline silicon solar cell module manufactured in Example 1. FIG.

  The polycrystalline silicon ingot manufacturing apparatus of the present invention includes a crucible having an upper opening, a heating unit that is provided on the outer periphery of the crucible and heats and melts the silicon raw material housed in the crucible, the crucible and the heating unit And a cover that has an inert gas introduction hole and that covers the upper opening of the crucible so as to be openable and closable, and an inert gas that is introduced into the inert gas introduction hole. An active gas introduction pipe, and is configured to produce a high-quality polycrystalline silicon ingot by unidirectionally solidifying the silicon melt.

A generally used crucible made of graphite or quartz (SiO ₂ ) can be used as the crucible.
As the heating unit, a resistance heating type heater can be used. In addition to such a heater, a heating element made of a material having high conductivity such as graphite or carbon provided on the outer periphery of the crucible is used as the induction heating coil. The crucible may be heated by heating.

The moving mechanism may move the crucible relative to the heating unit, or may move the heating unit relative to the crucible. In addition to simplifying the structure of the polycrystalline silicon ingot manufacturing apparatus, it is preferable to employ a moving mechanism that moves the crucible with respect to the heating unit. For example, a crucible is formed by a pneumatic or hydraulic cylinder mechanism, a link mechanism, a ball screw mechanism, or the like. Can be moved up and down.
The material of the cover is not particularly limited as long as it is a material excellent in heat resistance and strength, and examples thereof include graphite, SiO ₂ , silicon carbide (SiC), etc. Among these, oxidation resistance, durability, SiC is preferable from the viewpoint of mixing impurities into Si. The cover and the inert gas introduction pipe will be described later in detail.

The polycrystalline silicon ingot manufacturing apparatus of the present invention may be configured as follows.
(1) The inert gas introduction pipe may be extendable or retractable. In this way, even if the crucible and the heating unit move relatively vertically, the ingot solidification is completed because the inert gas can be continuously introduced into the space above the crucible covered with the cover. Until then, the CO gas partial pressure in the crucible can be kept low. Further, even if the silicon raw material is charged up to a position higher than the upper opening of the crucible, the inert gas introduction tube does not get in the way.
In addition, the inert gas introduction pipe can be specifically configured as the following (2) or (3).

(2) The inert gas introduction pipe is configured to introduce the inert gas into the first pipe into which the inert gas supplied from the inert gas supply source is introduced, and the inert gas introduction hole of the cover. It has 1 pipe | tube and the 2nd pipe | tube arrange | positioned so that an up-down direction slide is possible, and it may be comprised so that the movement of the relative up-down direction of the said crucible and the said heating part can be followed. In this case, the first tube may be slidably inserted into the second tube, and conversely, the second tube may be slidably inserted into the first tube. The material for the first and second tubes is not particularly limited as long as the material is excellent in heat resistance and strength, and examples thereof include SiC, Al ₂ O ₃ , SiO ₂ , and graphite. Of these, SiC is particularly preferable from the viewpoints of oxidation resistance, durability, and impurity incorporation into Si.

(3) A part or all of the inert gas introduction pipe may be a flexible pipe, and may be configured to be able to follow the relative vertical movement of the crucible and the heating unit.

(4) The polycrystalline silicon ingot manufacturing apparatus of the present invention may further include a support member that is provided on the outer periphery of the crucible and supports the lower end of the cover. In this case, the material of the support member is not particularly limited as long as it is a material excellent in heat resistance and strength, and the same material as that of the crucible can be used. Further, the support member may be an outer crucible that houses the crucible. By supporting the cover with the support member, it is possible to avoid the problem that when the cover is installed on the crucible, the deformation of the crucible is promoted by the weight of the cover.

(5) The cover may include a peripheral wall that rises along an edge of the upper opening of the crucible, and a lid that has an inert gas introduction hole and is detachably attached to the peripheral wall. By configuring the cover in this manner, the lid can be removed from the peripheral wall, and the silicon raw material can be easily loaded into the crucible up to a position higher than the upper opening of the crucible, and the silicon raw material loading amount is increased. be able to. Furthermore, in this state, the upper opening of the peripheral wall is covered with a lid, the silicon raw material is melted while introducing an inert gas into the crucible, and the molten silicon melt is unidirectionally solidified to produce a polycrystalline silicon ingot. Therefore, it is possible to obtain a high-quality and large-sized polycrystalline silicon ingot in which almost no SiC foreign matter is mixed.

  As a result, the cost per unit weight of a high-quality polycrystalline silicon ingot can be reduced, so that a polycrystalline silicon material obtained by processing a polycrystalline silicon ingot (obtained by processing a polycrystalline silicon ingot). Polycrystalline silicon block and polycrystalline silicon wafer obtained by processing the polycrystalline silicon in block), polycrystalline silicon solar cell manufactured using the polycrystalline silicon material (using the polycrystalline silicon material) The manufactured polycrystalline silicon solar battery cell and the polycrystalline silicon solar battery module manufactured using the polycrystalline silicon solar battery cell) can be manufactured at low cost while maintaining high quality.

(6) The peripheral wall may be configured such that the inner surface thereof is disposed on the inner side of the inner surface of the upper opening edge of the crucible. In this way, even if the silicon melt adheres to the peripheral wall, it flows down into the crucible. In addition, it is possible to prevent the silicon raw material from collapsing and the silicon melt from splashing out of the crucible when the silicon raw material is melted in the crucible. It will not decrease.

(7) The upper opening edge of the crucible may be square. In this case, the peripheral wall of the cover has a pair of first plates that rise along two opposing sides of the quadrangular upper opening edge of the crucible, and the other opposing ones of the quadrangular upper opening edge of the crucible. It is composed of a pair of second plate members that rise along two sides, the pair of first plate members has upper opening-like notches on both ends in the longitudinal direction, and the pair of second plates is on both ends in the longitudinal direction. And the peripheral wall may be configured to be assembled in a lattice shape by fitting the notches of the pair of second plate members into the notches of the pair of first plate members. If it does in this way, a peripheral wall can be produced easily.

(8) The cover body of the cover member may be composed of a plurality of plate members that can be divided. If it does in this way, manufacture of a lid will become easy, and handling of a lid at the time of loading a silicon raw material in a crucible will become easy.

  Hereinafter, embodiments of a polycrystalline silicon ingot manufacturing apparatus of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a cross-sectional view showing when the raw material is melted in the first embodiment of the polycrystalline silicon ingot production apparatus of the present invention, and FIG. 2 is a cross-sectional view showing when the solidification is completed in the polycrystalline silicon ingot production apparatus of the first embodiment. . 3 is a perspective view showing a crucible in the polycrystalline silicon ingot manufacturing apparatus of the first embodiment, and FIG. 4A is a front view showing a first plate member of a cover in the polycrystalline silicon ingot manufacturing apparatus of the first embodiment. FIG. 4B is a front view showing a second plate member of the cover in the polycrystalline silicon ingot manufacturing apparatus of the first embodiment. 5 is a perspective view showing a cover body in the polycrystalline silicon ingot manufacturing apparatus of the first embodiment, and FIG. 6 shows one of the cover and the inert gas introduction pipe in the polycrystalline silicon ingot manufacturing apparatus of the first embodiment. It is a perspective view which shows a part.

(Polycrystalline silicon ingot production equipment)
This polycrystalline silicon ingot manufacturing apparatus F1 is provided in the crucible 1 provided on the outer periphery of the crucible 1 having an upper opening, the outer crucible 2 having an upper opening for accommodating the crucible 1, and the crucible 1 and the outer crucible 2. A heater (heating unit) 3 that heats and melts the contained silicon raw material Ms, a hydraulic cylinder mechanism (moving mechanism) 4 that raises and lowers the crucible 1 and the outer crucible 2 relative to the heater 3, and an inert gas introduction hole 5Ba. ₁ and a cover 5 that covers the upper opening of the crucible 1 so as to be openable and closable, and an inert gas introduction pipe 6 that introduces an inert gas into the inert gas introduction hole 5Ba ₁ , and at least the crucible 1 and the outer crucible 2 The heater 3 is housed in a heat insulating case 7. These are installed in a chamber (not shown) that can be hermetically sealed and evacuated.

  The crucible 1 is formed in a cubic shape having an upper opening 1a (see FIG. 3). Further, the outer crucible 2 is formed in a cubic shape having a size larger than that of the crucible 1. When the crucible 1 is housed in the outer crucible 2, the height of the upper opening edge 2 b of the outer crucible 2 is slightly higher than the height of the upper opening edge 1 b of the crucible 1.

Cylinder mechanism 4 includes a hydraulic cylinder body 4a having a rod 4a _1, and a lifting table 4b which is connected to the distal end of the rod 4a ₁ (upper), the outer crucible 2 is placed accommodating the crucible 1 onto the lifting table 4b Has been. A recess 4b ₁ is provided at the lower end of the lift 4b so that the lowered lift 4b does not collide with the hydraulic cylinder body 4a (see FIG. 2).

The heat insulating case 7 is made of, for example, a carbon-based heat insulating material and is supported above the hydraulic cylinder body 4a in the chamber by a support member (not shown). In the heat insulating case 7, a hole 7 a through which the lifting platform 4 b is inserted and an inert gas exhaust port 7 b are formed in the bottom wall at the lower end. Note that the inert gas exhaust port 7b may be omitted, and the exhaust gas may be exhausted from the gap of the hole 7a.
In the case of Embodiment 1, the upper part of the heat insulation case 7 is a cylindrical space portion 7c in which a second pipe 6b of an inert gas introduction pipe 6 to be described later can be moved up and down. Needless to say, the heat insulating case 7 and the chamber are provided with doors for loading the silicon raw material Ms into the crucible 1 and taking out the polycrystalline silicon ingot Mi manufactured from the crucible 1.

  Although not shown, a thermocouple is disposed in the vicinity of the center of the upper surface of the lifting platform 4b in order to detect the temperature of the silicon raw material Ms in the crucible 1. The lifting platform 4 b includes a position detector that detects the vertical position of the crucible 1. In addition, a control thermocouple is disposed to detect the temperature of the heater 3. The outputs of these thermocouples and position detectors are input to a control device (not shown), whereby the heating state by the heater 3 is controlled.

Cover 5 includes a peripheral wall 5A which rises along the upper opening edge 1b of the crucible 1, and a lid 5B releasably attached to on the peripheral wall 5A which has the inert gas introduction hole 5Ba _1.
More specifically, as shown in FIGS. 4A, 4B, and 6, the peripheral wall 5A of the cover 5 extends along two opposing sides of the square upper opening edge 1b of the crucible 1. It consists of a pair of first plate members 5Aa that rises and a pair of second plate members 5Ab that rises along the other two opposite sides of the square upper opening edge 1b of the crucible 1. In addition, 1st and 2nd board | plate material 5Aa and 5Ab are the members which formed the notch mentioned later in the rectangular board material of the same size.

The first plate member 5Aa The pair of the longitudinal ends on the side edge which has a notch 5Aa ₁ of the upper opening shape, and has a notch 5Aa ₂ rectangles the lower edge of the longitudinal ends. The notch 5Aa ₁ is formed from the upper edge of the first plate 5Aa to the middle position in the width direction (perpendicular to the longitudinal direction), and the notch 5Aa ₂ is predetermined in the width direction from the lower edge of the first plate 5Aa. It is formed by the dimension L _1. The predetermined dimension L ₁ is larger than the difference between the height of the upper opening edge 2 b of the outer crucible 2 and the height of the upper opening edge 1 b of the crucible 1 in a state where the crucible 1 is housed in the outer crucible 2. Small dimensions.

On the other hand, the pair of second plate members 5Ab has a notch 5Ab ₁ having a downward opening at the lower edge on both ends in the longitudinal direction, and a rectangular notch 5Ab ₂ on the lower edge at both ends in the longitudinal direction. . The notch 5Ab ₁ is formed from the lower edge of the second plate member 5Ab to an intermediate position in the width direction, and the notch 5Ab ₂ is formed with a predetermined dimension L ₂ in the width direction from the lower edge of the second plate member 5Ab. . The predetermined dimension L ₂ is the same as the dimension L ₁ with the notch 5Aa ₂ of the first plate member 5Aa.

Wall 5A can be assembled in a lattice pattern by fitting the 5Ab _1-out each notch of the pair of second plate members 5Ab to 5Aa _1-out each notch of the pair of first plate 5Aa, square frame portion of the peripheral wall 5A is substantially It is a natural part.
The peripheral wall 5 </ b> A configured in this way is installed on the upper opening edge 1 b of the outer crucible 2 that houses the crucible 1. At this time, the rectangular cutouts 5Aa ₂ and 5Ab ₂ (a total of 8 places) of the peripheral wall 5A are placed on the upper opening edge 1b of the outer crucible 2.

The peripheral wall 5 </ b> A is supported by the outer crucible 2, so that the peripheral wall 5 </ b> A floats from the crucible 1. Thereby, a gap is formed between the crucible 1 and the peripheral wall 5A. Further, the inner surface 5Af of the peripheral wall 5A is disposed on the inner side of the inner surface 1f of the upper opening edge 1b of the crucible 1.
Therefore, the lengths of the first and second plate members 5Aa and 5Ab of the peripheral wall 5A, the formation positions and dimensions of the notches 5Aa ₁ , 5Aa ₂ , 5Ab ₁ , and 5Ab ₂ are determined so as to obtain such an installation state. do it.
The square frame portion of the peripheral wall 5 </ b> A is a storage space for the silicon raw material Ms loaded up to a position higher than the upper opening 1 a of the crucible 1. The silicon raw material Ms can be loaded into the crucible 1 to such an extent that the silicon melt in which the silicon raw material Ms is completely dissolved in the crucible 1 does not overflow from the crucible 1. Therefore, the volume of the accommodation space of the peripheral wall 5A, that is, the height H of the peripheral wall 5A may be determined in consideration of the loading amount of the silicon raw material Ms. However, at the same time, it is necessary to consider the restrictions on the apparatus (the size of the inside of the chamber, the amount of crucible lowering during ingot unidirectional solidification, etc.).

As shown in FIGS. 5 and 6, the cover 5 </ b> B of the cover member 5 is composed of three rectangular plate members 5 </ b> Ba, 5 </ b> Bb, 5 </ b> Bc that can be divided. By arranging the long sides of these three plate members 5Ba, 5Bb, 5Bc adjacent to each other on the peripheral wall 5A, a square lid body 5B larger than the peripheral wall 5A (square frame portion) is formed. The inert gas introduction hole 5Ba ₁ is formed at the center position of the middle plate member 5Ba.

As shown in FIGS. 1, 2, and 6, the inert gas introduction pipe 6 includes a first pipe 6 a into which an inert gas supplied from an inert gas supply source (not shown) is introduced, and a cover 5. has a first pipe 6a to introduce an inert gas into the inert gas introduction hole 5Ba ₁ and vertically slidably connected to the second pipe 6b, the movement of the relative vertical direction between the crucible 1 and the heater 3 It has a double pipe structure that can be expanded and contracted so that it can follow.

In the case of the first embodiment, the first pipe 6 a passes through the upper part of the chamber and the upper part of the heat insulating case 7 and is arranged in the vertical direction, and its tip (lower end) is located near the height of the heater 3.
The second tube 6 b is a tube having an inner diameter into which the first tube 6 a can be inserted, and is placed on the lid 5 </ b> B of the cover 5. In the case of Embodiment 1, the outer flange 6b ₁ is provided at the lower end of the second pipe 6b so that the second pipe 6b is stabilized on the lid 5B. Although the outer flange 6b ₁ may be omitted, by providing the outer flange 6b ₁ at the lower end of the second pipe 6b, the lower end opening of the second pipe 6b is made an inert gas of the lid 5B (plate material 5Ba). easily positioned to the position of the introduction hole 5Ba _1. In this case, for example, a recess having a shape matching the outer shape of the outer flange 6b ₁ is formed on the upper surface of the lid 5B.

Furthermore, the polycrystalline silicon ingot manufacturing apparatus F1 of Embodiment ₁ is configured as follows in order to always arrange the inert gas introduction hole 5Ba ₁ of the lid 5B on the axial center of the first pipe 6a. It is configured. That is, a notch into which the outer peripheral portion of the lid 5B fits tightly is formed at the lattice-like upper edge of the peripheral wall 5A of the cover 5. Further, the outer crucible 2 is installed in a manner to be fitted into the lifting platform 4b. In addition, the crucible 1 is installed at substantially the same position in the outer crucible 2. With this configuration, the new crucible 1 and the outer crucible 2 are used every time the ingot is manufactured, the peripheral wall 5A of the cover 5 is set on the outer crucible 2, and the lid 5B is placed on the peripheral wall 5A after the raw materials are charged. Even when placed, the inert gas introduction hole 5Ba ₁ of the lid 5B is always arranged on the axis of the first tube 6a.

(Polycrystalline silicon ingot manufacturing method)
In the polycrystalline silicon ingot manufacturing method using the polycrystalline silicon ingot manufacturing apparatus F1 of Embodiment 1 configured as described above, first, the silicon raw material Ms is loaded into the crucible 1 outside the manufacturing apparatus F1. At this time, the crucible 1 is installed in the outer crucible 2, the peripheral wall 5 </ b> A of the cover 5 is installed on the outer crucible 2, and then the silicon raw material Ms is charged into the crucible 1. And the cover body 5B is installed on 5 A of surrounding walls, and the outer crucible 2 is installed on the raising / lowering stand 4b in a descent | fall position (refer FIG. 2).

  Then, the 2nd pipe | tube 6b is dropped and mounted on the cover body 5B, and a chamber is sealed. And the crucible 1 is raised to a manufacture start position with the cylinder mechanism 4 (refer FIG. 1). Next, the inside of the chamber is evacuated (evacuated), and an inert gas is introduced into the chamber to perform gas replacement. At this time, the inert gas introduced into the cover 5 from the first pipe 6a of the inert gas introduction pipe 6 flows out of the cover 5 through the gap between the cover 5 and the crucible 1, and enters the heat insulating case 7 and the chamber. It is filled and discharged to the outside from the inert gas exhaust port 7b.

Thereafter, while introducing an inert gas into the cover 5, the heater 3 heats the crucible 1 through the outer crucible 2 and the cover 5, thereby heating and melting the silicon raw material Ms. After confirming that all of the silicon raw material Ms has been melted, the crucible 1 is slowly lowered by the cylinder mechanism 4 at a constant speed (for example, about 30 mm / hour). Start directional solidification. At this time, since the second pipe 6b slides downward with respect to the first pipe 6a, the inert gas introduction pipe 6 gradually extends to introduce the inert gas into the cover 5.
Then, the crucible 1 is lowered to the lowest position (see FIG. 2), the completion of solidification is confirmed, an annealing process is performed after raising the crucible 1, and then the crucible 1 is taken out from the chamber by the ingot taking-out process. The polycrystalline silicon ingot Mi manufactured from is taken out.

(Polycrystalline silicon block)
The polycrystalline silicon block of the present invention can be obtained by processing the polycrystalline silicon ingot of the present invention into a desired size.
The polycrystalline silicon block can be obtained, for example, by cutting a surface portion where impurities such as a crucible material may be diffused in the polycrystalline silicon ingot of the present invention using a known apparatus such as a band saw. it can.
Moreover, you may grind | polish the surface of a polycrystalline silicon block as needed.

(Polycrystalline silicon wafer)
The polycrystalline silicon wafer of the present invention can be obtained by processing the polycrystalline silicon block of the present invention.
The polycrystalline silicon wafer can be obtained, for example, by slicing the polycrystalline silicon block of the present invention to a desired thickness using a known apparatus such as a multi-wire saw. Currently, it is often processed to a thickness of 170 μm to 200 μm.
Further, if necessary, the surface of the polycrystalline silicon wafer may be polished.

(Polycrystalline silicon solar cells)
The polycrystalline silicon solar battery cell of the present invention is manufactured using the polycrystalline silicon wafer of the present invention.
A polycrystalline silicon solar cell can be manufactured, for example, by a known solar cell process using the polycrystalline silicon wafer of the present invention. That is, in the case of a silicon wafer doped with a p-type impurity by a known method using a known material, an n-type impurity is doped to form an n-type layer to form a pn junction, and the surface electrode And a back surface electrode is formed and a polycrystalline silicon solar cell is obtained.

(Polycrystalline silicon solar cell module)
The polycrystalline silicon solar cell module of the present invention is formed by electrically connecting a plurality of polycrystalline silicon solar cells of the present invention.
For example, the polycrystalline silicon solar battery module uses the polycrystalline silicon solar battery cell of the present invention to electrically connect a plurality of solar battery cells with an interconnector (conductive member) by a known solar battery module process. And it can be manufactured by sealing it.

(Embodiment 2)
FIG. 7 is a partially enlarged cross-sectional view showing an inert gas introducing portion in Embodiment 2 of the polycrystalline silicon ingot manufacturing apparatus of the present invention.
The second embodiment is different from the first embodiment only in the configuration of the inert gas introduction pipe, and the other configurations in the second embodiment are the same as those in the first embodiment. Therefore, only different points will be described below.

  The inert gas introduction pipe 16 in the polycrystalline silicon ingot manufacturing apparatus according to the second embodiment includes a first pipe 16a into which an inert gas supplied from an inert gas supply source (not shown) is introduced, and an inert gas introduction to the cover. It has the 1st pipe | tube 16a and the 2nd pipe | tube 16b connected so that an up-down direction sliding was possible so that an inert gas may be introduce | transduced into a hole, and the 2nd pipe | tube 16b is slidably inserted in the 1st pipe | tube 16a. In this way, the inert gas introduction pipe 16 may have a double pipe structure that can be expanded and contracted.

(Embodiment 3)
FIG. 8 is a cross-sectional view showing the start of production in the third embodiment of the polycrystalline silicon ingot production apparatus of the present invention, and FIG. 9 is a cross-sectional view showing the end of production in the polycrystalline silicon ingot production apparatus of the third embodiment. . In FIGS. 8 and 9, the same elements as those in FIGS. 1 and 2 are denoted by the same reference numerals. 8 and 9, the silicon raw material and the manufactured polycrystalline silicon ingot are not shown.

  In the polycrystalline silicon ingot manufacturing apparatus F3 of Embodiment 3, a part or all of the inert gas introduction pipe 26 is formed of a flexible pipe and is configured to be able to follow the relative vertical movement of the crucible 1 and the heater 3. ing. In this case, the upper part of the heat insulation case 27 is a space in which the inert gas introduction pipe 26 can be bent.

Furthermore, in the case of the third embodiment, for example, at the distal end of the inert gas introduction pipe 26, the distal end of the flexible inert gas introduction pipe 26 does not deviate from the inert gas introduction hole 5Ba ₁ of the lid 5B of the cover 5. A connecting pipe 27 is inserted. The connecting pipe 27 has an outer flange 27a at the lower end, and as described above, the outer flange 27a is positioned in a recess formed on the upper surface of the lid 5B.
Or you may employ | adopt the following retaining structures. In this case, for example, one or more protrusions are provided on the inner peripheral surface of the inert gas introduction hole 5Ba ₁ of the lid 5B. Further, a connecting pipe not having the outer flange 27a is inserted into the distal end of the flexible inert gas introduction pipe 26, and an inverted L-shaped groove for inserting the protrusion is formed on the outer peripheral surface of the connecting pipe. To do. In this way, when the tip of the connection pipe is inserted into the inert gas introduction hole 5Ba ₁ , the protrusion is inserted into the groove, and if the connection pipe is turned a little, the protrusion enters the depth of the groove. The active gas introduction pipe 26 is prevented from coming off from the inert gas introduction hole 5Ba ₁ .
Other configurations in the third embodiment are substantially the same as those in the first and second embodiments.

(Other embodiments)
1. In the first embodiment (FIGS. 1 and 2) and the third embodiment (FIGS. 8 and 9), the hydraulic cylinder mechanism is exemplified as the moving mechanism. However, for example, a ball screw mechanism may be employed. In this case, it is preferable that the rotation shaft of the ball screw mechanism is not inserted into the heat insulating cover.

2. The height of the upper opening edge 1 b of the crucible 1 may be slightly higher than the height of the upper opening edge 2 b of the outer crucible 2. In this case, instead of the first and second plate members 5Aa and 5Ab (see FIGS. 4A and 4B) constituting the peripheral wall of the cover, notches in the first and second plate members 5Aa and 5Ab are provided. This can be dealt with by forming the peripheral wall using the first and second plate members having the protruding pieces projecting 5Aa ₂ and 5Ab ₂ downward from the lower edge by dimensions L ₁ and L ₂ .

3. The inert gas introduction pipe 6 does not necessarily have a double structure. In a limited apparatus, in order to increase the loading amount of the silicon raw material as much as possible, it is necessary to attach a cover having a high height. For this purpose, it is preferable to use a triple or more multiple structure. However, since the structure becomes complicated, for example, troubles such as SiO powder generated from the silicon melt accumulate in the movable part and become unable to move can be considered, which involves a risk.
The inert gas introduction pipe 6 can be a single pipe. However, in order to increase the loading amount of the silicon raw material, depending on the shape of the apparatus, it is necessary to take measures such as melting silicon with the crucible position lowered. In this case, since the melted silicon melt flows down to the bottom of the crucible having a low temperature, there is a risk of crucible cracking. Further, since the silicon melted at the upper part of the raw material silicon may come into contact with the inert gas introduction pipe 6 and contaminate the raw material, the inert gas introduction pipe 6 is preferably double or more.

Example 1
<Manufacture of polycrystalline silicon ingot>
In Example 1, first, a p-type polycrystalline silicon ingot was manufactured using the polycrystalline silicon ingot manufacturing apparatus F1 of Embodiment 1 described with reference to FIGS.
At this time, a crucible 1 having an internal volume of 830 mm in length, 830 mm in width, and 420 mm in height was used.
Further, in the used cover 5, the distance from the upper opening edge 1b of the crucible 1 to the lower surface of the lid 5B is 200 mm, and the distance between the first plate members 5Aa facing each other and the distance between the second plate members 5Ab facing each other. Was 815 mm, and the plate thickness of the lid 5B was 15 mm.
Moreover, as the 2nd pipe | tube 6b of the inert gas introduction pipe | tube 6, the thing of length 180mm was used.
The outer crucible 2 was 15 mm higher than the upper opening edge 1b of the crucible 1 in the outer crucible 2.

Next, the crucible 1, the cover 5 and the like were all set at predetermined positions in the apparatus, and then the silicon raw material Ms was loaded into the crucible 1. In order to reduce the cost of the polycrystalline silicon ingot, it is desirable to put as much silicon raw material Ms as possible into the crucible 1. Therefore, when the silicon raw material Ms was charged as much as possible, the loading amount was 565 kg.
Next, the chamber door was closed, the crucible 1 was raised to the initial position shown in FIG. 1, evacuation was performed, and the silicon raw material Ms was heated to 800 ° C. by the heater 3. Then, while introducing argon gas from the inert gas introduction pipe 6 at a flow rate of 40 L / min, the mixture was heated to 1550 ° C. and waited until all of the silicon raw material Ms was melted. Next, it hold | maintained for 30 minutes by melting | fusing point +15 degreeC of silicon | silicone, Then, temperature control and crucible position control were performed according to the predetermined | prescribed recipe.

At the start of silicon melting, the tip of the first tube 6a of the inert gas introduction tube 6 is inserted into the cover 5 up to a position 10 mm from the lower surface of the lid 5B, and the crucible 1 is maximized from the initial position during unidirectional solidification. It was lowered 200 mm. Therefore, in Example 1, the state where the first pipe 6a of the inert gas introduction pipe 6 was inserted into the second pipe 6b was maintained until the solidification of the upper surface of the ingot was completed.
After confirming that solidification was completed up to the upper surface of the ingot from the output tendency of the heater 3, annealing was performed at 1200 ° C. for 2 hours, cooled, and the ingot was taken out.
When the upper surface of the ingot was visually confirmed, the ingot of Example 1 showed a metallic luster on the entire surface.

<Block processing>
Next, the crucible 1 was broken, the polycrystalline silicon ingot Mi was taken out, the bottom of the ingot was fixed with a bond, and 25 156 mm square blocks were cut out with a band saw. Subsequently, the end portions of the blocks corresponding to the upper and lower portions of the ingot were each cut by about 15 mm. Thereafter, the side surfaces of each block were polished. When SiC foreign material is seen on the side surface of the block, the wire saw may be disconnected in the subsequent slicing step, so that the block foreign material is defective, and the results are shown in Table 1. In Table 1, the numerical values of Example 1 and Example 2 described later are ratios (%) when the result of Comparative Example 1 described later is 100.

<Slicing>
Next, the polycrystalline silicon block obtained by the block processing was sliced to a thickness of 180 μm with a wire saw. After processing, the surface was washed to remove dirt and visually inspected. A wafer in which a step defect considered to be caused by a SiC foreign material and a foreign material were confirmed was regarded as a wafer foreign material defect, and the results are shown in Table 1.

<Solar cell formation process>
Next, the polycrystalline silicon wafer obtained by the slicing process was put into the following solar cell forming process.
First, as shown in FIG. 10 (A), a p-type polycrystalline silicon wafer 11 having a thickness of about 170 μm is prepared. As shown in FIG. 10 (B), PSG (phosphorus silicate) is formed on the surface of the polycrystalline silicon wafer 11. Glass) liquid 41 was applied.

  Next, phosphorus was diffused from the PSG liquid 41 to the polycrystalline silicon wafer 11 by heating the polycrystalline silicon wafer 11 after the application of the PSG liquid 41. Thus, as shown in FIG. 10C, an n + layer 42 having a thickness of 0.3 μm was formed on the surface of the polycrystalline silicon wafer 11 on the light receiving surface side. At this time, a PSG film 41 a having a thickness of about 1 μm was formed on the n + layer 42. Thereafter, as shown in FIG. 10D, the PSG film 41a formed during the diffusion of phosphorus was removed.

Next, as shown in FIG. 10E, an antireflection film 43 made of a silicon nitride film was formed on the n + layer 42 of the polycrystalline silicon wafer 11 to a thickness of 0.08 μm.
Next, as shown in FIG. 10F, an aluminum paste 44a was applied to the back surface (non-light-receiving surface) of the polycrystalline silicon wafer 11. Then, the polycrystalline silicon wafer 11 after the application of the aluminum paste 44a is baked at 770 ° C. to diffuse aluminum from the aluminum paste 44a to the back surface of the polycrystalline silicon wafer 11, and as shown in FIG. The aluminum electrode 44 and the p + layer 45 were simultaneously formed on the back surface of the polycrystalline silicon wafer 11.

  Next, as shown in FIG. 10H, a silver paste 46a is applied on the surface of the antireflection film 43, and a silver paste 47a is applied on the back surface of the polycrystalline silicon wafer 11, and then fired at 700 ° C. did. As a result, as shown in FIG. 10 (I), a silver electrode 46 as a front electrode electrically connected to the n + layer 42 is formed, and a silver electrode electrically connected to the back surface of the polycrystalline silicon wafer 11. 47 was formed, and a polycrystalline silicon solar battery cell 40 was manufactured.

  Thereafter, characteristic inspection was performed in the final process. In the characteristic inspection, under the solar simulator, IV measurement in a state where light irradiation was performed and reverse direction IV measurement in a state where light was not irradiated were performed. In particular, when SiC foreign matter is present in the surface of the polycrystalline silicon wafer, there is a concern about leakage failure (hereinafter referred to as Id failure) in a state where light is not irradiated. This is presumably because the SiC foreign matter generally contains nitrogen impurities, which are n-type dopants, and thus is a low-resistance n-type foreign matter. Table 1 shows the Id defect rate results for Example 1.

<Solar cell modularization process>
The polycrystalline silicon solar battery module 50 shown in FIG. 11 was manufactured by electrically connecting a plurality of polycrystalline silicon solar battery cells 40 of Example 1 in series.
That is, the silver electrode 46 which is a surface electrode on the light receiving surface side of one polycrystalline silicon solar cell 40 and the silver electrode 47 on the back surface side of the other polycrystalline silicon solar cell 40 which are arranged adjacent to each other. Were electrically connected by a conductive member 51 called an interconnector. Thereby, a solar cell string in which these polycrystalline silicon solar cells 40 were electrically connected in series was manufactured.

  And the said solar cell string was sealed in the sealing material 54 installed between the transparent substrate 52 and the protective sheet 53, and the polycrystalline-silicon solar cell module was manufactured. Here, a glass substrate was used as the transparent substrate 52. Further, a PET (polyethylene terephthalate) film was used as the protective sheet 53. Further, EVA (ethylene vinyl acetate) was used as the sealing material 54.

(Example 2)
In Example 2, a polycrystalline silicon ingot was manufactured in the same manner as in Example 1 except that the length of the second pipe 6b of the inert gas introduction pipe 6 was 130 mm.
The length of the second pipe 6b of the inert gas introduction pipe 6 used in the second embodiment is shorter than the length of the second pipe 6b of the inert gas introduction pipe 6 used in the first embodiment. When the crucible 1 was lowered by a maximum of 200 mm, the tip (lower end) of the first tube 6a and the upper end of the second tube 6b were separated by 45 mm. That is, the first pipe 6a is in a state of being removed from the second pipe 6b.

Using the polycrystalline silicon ingot of Example 2, block processing and polishing were performed in the same manner as in Example 1. Further, in Example 2, similarly to Example 1, determination was made regarding block foreign body defects on the side surfaces of the blocks, and the results are shown in Table 1.
Next, the block of Example 2 was sliced and washed in the same manner as in Example 1, and the wafer foreign matter failure was determined by visual inspection. The results are shown in Table 1.
Using the wafer of Example 2, a polycrystalline silicon solar cell was formed in the same manner as in Example 1, and Id defect inspection was performed. The results are shown in Table 1.
Thereafter, using the solar battery cell of Example 2, a polycrystalline silicon solar battery module was produced in the same manner as in Example 1.

(Comparative Example 1)
As Comparative Example 1, a polycrystalline silicon ingot was manufactured in the same manner as in Example 1 except that a polycrystalline silicon ingot manufacturing apparatus without the cover 5 and the second tube 6b was used. In Comparative Example 1, the loading amount of the silicon raw material Ms into the crucible 1 was 450 kg.
When the upper surface of the ingot of Comparative Example 1 was visually confirmed, cloudiness was observed, and a green foreign substance thought to be SiC was found on a part of the upper surface.

Using the polycrystalline silicon ingot of Comparative Example 1, block processing and polishing were performed in the same manner as in Example 1. Further, in Comparative Example 1 as well as in Example 1, determination was made regarding block foreign body defects on the side surfaces of the blocks, and the results are shown in Table 1.
Next, the block of Comparative Example 1 was sliced and washed in the same manner as in Example 1, and the wafer foreign matter failure was determined by visual observation. The results are shown in Table 1.
Using the wafer of Comparative Example 1, a polycrystalline silicon solar battery cell was subjected to Id defect inspection in the same manner as in Example 1, and the results are shown in Table 1.
Thereafter, using the solar battery cell of Comparative Example 1, a polycrystalline silicon solar battery module was produced in the same manner as in Example 1.

From the results of Table 1, it was confirmed that Examples 1 and 2 had better results with respect to block foreign matter, wafer foreign matter and Id defect than Comparative Example 1, and that Example 1 was particularly good.
In addition, regarding the production of a polycrystalline silicon solar battery module using the polycrystalline silicon solar battery cells of Examples 1 and 2 and Comparative Example 1, there is no significant difference in characteristics and yield. Since there is a difference in the loading amount of the silicon raw material, and a difference due to SiC foreign matter is seen in the block yield, the slice yield, and the solar cell inspection yield, the cost of the module is shown in Example 1 <Example 2 << Comparison Example 1 was obtained. Therefore, the present invention makes it possible to supply a polycrystalline solar cell module to the market at a low price.

  The embodiments and examples herein are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Crucible 1a Upper opening 1b Upper opening edge 1f Inner surface of upper opening edge of crucible 2 Outer crucible (support member)
3 Heater (heating part)
4 Cylinder mechanism (moving mechanism)
5 Cover 5A wall 5Af wall of the inner surface 5Aa first plate 5Ab second plate 5Aa _1, 5Aa _2, 5Ab _1, 5Ab _2, the notch 5B lid 5Ba, 5Bb, 5Bc plate 5Ba ₁ inert gas inlet 6 and 16, 26 Inert gas introduction pipe 6a, 16a First pipe 6b, 16b Second pipe 40 Polycrystalline silicon solar cell (solar cell)
50 polycrystalline silicon solar cell module F1, F2 polycrystalline silicon ingot manufacturing equipment Mi polycrystalline silicon ingot Ms silicon raw material

Thus, according to the present invention, the crucible having the upper opening, the heating unit that is provided on the outer periphery of the crucible and heats and melts the silicon raw material stored in the crucible, and the crucible and the heating unit are relatively A vertical movement mechanism, a cover having an inert gas introduction hole and covering the upper opening of the crucible so as to be openable and closable, and introducing an inert gas into the inert gas introduction hole A tube, and a support member provided on an outer periphery of the crucible and supporting a lower end of the cover,
A first pipe into which an inert gas supplied from an inert gas supply source is introduced so that the inert gas introduction pipe can be expanded or contracted, and an inert gas into the inert gas introduction hole of the cover. The second tube connected to the first tube so as to be slidable in the vertical direction, and configured to follow the relative vertical movement of the crucible and the heating unit,
The cover rises along the edge of the upper opening of the crucible and has a peripheral wall whose upper end is positioned above the edge of the upper opening, an inert gas introduction hole, and is detachably mounted on the peripheral wall. An apparatus for producing a polycrystalline silicon ingot is provided.

In here, in this specification, as a concept including a "silicon block" and "silicon wafer", referred to as "silicon material". Thus, for example, what is described as “polycrystalline silicon material” is meant to include “polycrystalline silicon block” and “polycrystalline silicon wafer”.

It is sectional drawing which shows the time of the raw material fusion | melting in Embodiment 1 of the polycrystalline-silicon ingot manufacturing apparatus of this invention. It is sectional drawing which shows the time of completion of solidification in the polycrystalline silicon ingot manufacturing apparatus of Embodiment 1. FIG. 3 is a perspective view showing a crucible in the polycrystalline silicon ingot manufacturing apparatus of Embodiment 1. It is a front view which shows the 1st board | plate material of the cover in the polycrystalline silicon ingot manufacturing apparatus of Embodiment 1. FIG. It is a front view which shows the 2nd board | plate material of the cover in the polycrystalline silicon ingot manufacturing apparatus of Embodiment 1. FIG. It is a perspective view which shows the cover body of the cover in the polycrystalline silicon ingot manufacturing apparatus of Embodiment 1. FIG. FIG. 3 is a perspective view showing a part of a cover and an inert gas introduction pipe in the polycrystalline silicon ingot manufacturing apparatus of the first embodiment. It is a partial expanded sectional view which shows the inert gas introducing | transducing part in Embodiment 2 of the polycrystalline-silicon ingot manufacturing apparatus of this invention. It is sectional drawing which shows the time of raw material fusion | melting in Embodiment 3 (reference example) of a polycrystal silicon ingot manufacturing apparatus. It is sectional drawing which shows the time of the completion of solidification in the polycrystalline silicon ingot manufacturing apparatus of Embodiment 3. 1 is a first diagram illustrating a solar cell forming step in Example 1. FIG. FIG. 3 is a second diagram showing a solar battery cell forming step in Example 1. FIG. 5 is a third diagram illustrating a solar cell formation step in Example 1. FIG. 6 is a fourth diagram showing a solar cell formation step in Example 1. FIG. 10 is a fifth diagram illustrating a solar cell formation step in Example 1; FIG. 10 is a sixth diagram illustrating a solar cell formation step in Example 1. FIG. 10 is a seventh diagram illustrating a solar battery cell formation step in Example 1; It is an 8th figure which shows the photovoltaic cell formation process in Example 1. FIG. FIG. 10 is a ninth diagram illustrating the solar cell formation step in Example 1. 2 is a partial cross-sectional view showing a polycrystalline silicon solar cell module manufactured in Example 1. FIG.

Further, a polycrystalline silicon ingot production apparatus of the present invention is constructed as follows.
(1) the inert gas inlet tube, be stretchable or bending. This ensures, moving the crucible and the heating unit is the relatively vertical direction, it is possible to continue introducing an inert gas into the space of the crucible top covered by a cover, until the ingot solidification completion The CO gas partial pressure in the crucible can be kept low. Further, even if the silicon raw material is charged up to a position higher than the upper opening of the crucible, the inert gas introduction tube does not get in the way.
In addition, the inert gas introduction pipe can be specifically configured as shown in (2 ) below.

(2) The inert gas introduction pipe is configured to introduce the inert gas into the first pipe into which the inert gas supplied from the inert gas supply source is introduced, and the inert gas introduction hole of the cover. It has one pipe and a second pipe arranged to be slidable in the vertical direction, and is configured to be able to follow the relative vertical movement of the crucible and the heating unit. In this case, the first tube may be slidably inserted into the second tube, and conversely, the second tube may be slidably inserted into the first tube. The material for the first and second tubes is not particularly limited as long as the material is excellent in heat resistance and strength, and examples thereof include SiC, Al ₂ O ₃ , SiO ₂ , and graphite. Of these, SiC is particularly preferable from the viewpoints of oxidation resistance, durability, and impurity incorporation into Si.

( 3 ) The polycrystalline silicon ingot manufacturing apparatus of the present invention includes a support member that is provided on the outer periphery of the crucible and supports the lower end of the cover . As the material of the supporting support member is not particularly limited as long as it is a material excellent in heat resistance and strength, it is possible to use the same material as the crucible. Further, the support member may be an outer crucible that houses the crucible. By supporting the cover with the support member, it is possible to avoid the problem that when the cover is installed on the crucible, the deformation of the crucible is promoted by the weight of the cover.

(4) the cover, the peripheral wall top end you positioned above said upper opening edge I rising along the upper opening edge of the crucible, which has an inert gas inlet to Yes and a lid releasably attached to on the peripheral wall. By configuring the cover in this manner, the lid can be removed from the peripheral wall, and the silicon raw material can be easily loaded into the crucible up to a position higher than the upper opening of the crucible, and the silicon raw material loading amount is increased. be able to. Furthermore, in this state, the upper opening of the peripheral wall is covered with a lid, the silicon raw material is melted while introducing an inert gas into the crucible, and the molten silicon melt is unidirectionally solidified to produce a polycrystalline silicon ingot. Therefore, it is possible to obtain a high-quality and large-sized polycrystalline silicon ingot in which almost no SiC foreign matter is mixed.

Moreover, the polycrystalline silicon ingot manufacturing apparatus of the present invention may be configured as follows.
( 5 ) The peripheral wall may be configured such that the inner surface thereof is disposed on the inner side of the inner surface of the upper opening edge of the crucible. In this way, even if the silicon melt adheres to the peripheral wall, it flows down into the crucible. In addition, it is possible to prevent the silicon raw material from collapsing and the silicon melt from splashing out of the crucible when the silicon raw material is melted in the crucible. It will not decrease.

( 6 ) The upper opening edge of the crucible may be square. In this case, the peripheral wall of the cover has a pair of first plates that rise along two opposing sides of the quadrangular upper opening edge of the crucible, and the other opposing ones of the quadrangular upper opening edge of the crucible. It is composed of a pair of second plate members that rise along two sides, the pair of first plate members has upper opening-like notches on both ends in the longitudinal direction, and the pair of second plates is on both ends in the longitudinal direction. And the peripheral wall may be configured to be assembled in a lattice shape by fitting the notches of the pair of second plate members into the notches of the pair of first plate members. If it does in this way, a peripheral wall can be produced easily.

( 7 ) The cover body of the cover member may be composed of a plurality of plate members that can be divided. If it does in this way, manufacture of a lid will become easy, and handling of a lid at the time of loading a silicon raw material in a crucible will become easy.

(Embodiment 3 : Reference example )
FIG. 8 is a cross-sectional view showing the time when production of the polycrystalline silicon ingot production apparatus in Embodiment 3 (reference example) is started, and FIG. is there. In FIGS. 8 and 9, the same elements as those in FIGS. 1 and 2 are denoted by the same reference numerals. 8 and 9, the silicon raw material and the manufactured polycrystalline silicon ingot are not shown.

The present invention relates to a suitably polycrystalline silicon in Cum preparative manufacturing apparatus and a manufacturing how for use in solar cells.

  Recently, renewable energy has attracted attention for environmental problems on a global scale. Among them, solar cells are attracting a great deal of attention. There are several types of solar cells, including bulk, thin film, and dye sensitization. Among them, polycrystalline silicon solar cells using polycrystalline silicon wafers have the highest cost performance and the largest market. Accounted for. Therefore, in order to promote further spread of polycrystalline silicon solar cells, there is a demand for lowering the cost of polycrystalline silicon solar cells.

As a silicon crystal solar cell, an n-type layer is formed by a method such as diffusion on the surface of a p-type silicon substrate to which a small amount of a group III element such as B (boron) or Ga (gallium) is added. A pn junction type having a pn junction is most common. In addition, a p-type layer is formed on the surface of an n-type silicon substrate to which a small amount of a group V element such as P (phosphorus) is added, or an n- or p-type layer is grown on a p- or n-substrate by thin film growth. There are silicon crystal solar cells having various structures such as those having a structure in which n ⁺ and p ⁺ regions are formed on the back side of an n-type silicon substrate and electrodes are collected on the back side.

Polycrystalline silicon used for solar cells can be obtained by manufacturing a silicon ribbon or spherical silicon, but is generally manufactured by a manufacturing method called a casting method. In the casting method, for example, a silicon melt is held in a crucible made of silica, and then the silicon melt is unidirectionally solidified from the bottom side of the crucible to the liquid surface side to produce a polycrystalline silicon ingot. Thereafter, in general, the polycrystalline silicon ingot is processed into a prismatic block of an appropriate size by a band saw, and the block is sliced by a wire saw to obtain a wafer. A polycrystalline silicon solar cell is manufactured using the polycrystalline silicon wafer thus obtained, and a solar cell module is manufactured by modularizing a plurality of solar cells.
Here, in the following description of the present specification, the concept including “solar battery cell” and “solar battery module” is simply referred to as “solar battery”. Therefore, for example, what is described as “polycrystalline silicon solar cell” is meant to include “polycrystalline silicon solar cell” and “polycrystalline silicon solar cell module”.

  Silicon carbide foreign matter (SiC foreign matter) present in the polycrystalline silicon ingot causes various processing defects during block processing and block slicing of the polycrystalline silicon ingot. Since SiC is harder than silicon, the wire saw breaks during slicing. Alternatively, a defective wafer is generated due to a problem such as a step in the wafer or an increase in the in-plane thickness distribution of the wafer. Further, in order to prevent the wire saw from being disconnected in the slicing step, when SiC foreign matter is confirmed on the block surface, it is necessary to excise a portion where the SiC foreign matter has been confirmed in advance, but this significantly reduces the yield.

Further, also in the manufacturing process of the solar battery cell, if SiC foreign matter is present in the polycrystalline silicon wafer, a characteristic defect called Id defect is caused and yield is lowered. Here, the Id defect is defined as a defect in which the reverse current that flows when an appropriate reverse voltage is applied to the solar cell in the non-irradiation state exceeds the reference value. The reference value of the reverse voltage or reverse current to be applied is determined by the structure of the solar cell module, the number of solar cells in series, etc., when some of the solar cells connected in series are shaded, etc. It is determined for the purpose of suppressing the heat generation at.
In order to reduce the cost of the polycrystalline silicon solar cell, it is necessary to avoid the above-described reduction in processing yield and reduction in the characteristic yield of the solar cell. To that end, SiC foreign matter in the polycrystalline silicon ingot is required. Need to be reduced.

  The cause of the generation of SiC foreign matter is considered to be that carbon impurities are originally contained in the silicon raw material, and that carbon impurities are mixed into the silicon melt during casting. Even when a polysilicon raw material having a low carbon concentration is used, SiC foreign matter is generated in the ingot. Therefore, it is essential to reduce carbon impurities mixed during casting. As a mixing route of carbon impurities at the time of casting, SiO evaporated from the silicon melt (molten metal) reacts with a graphite member (for example, a graphite heating part, a carbon-based heat insulating material, etc.) that has become a high temperature in the furnace, and CO. A route is considered in which gas is generated and the CO gas is taken into the silicon melt.

  As a polycrystalline silicon ingot manufacturing apparatus for reducing the carbon impurity concentration, a crucible, an upper heating unit and a lower heating unit disposed above and below the crucible, and a gas for supplying an inert gas toward the silicon melt And a plate-like lid provided between the silicon melt and the upper heating part, and a through hole for inserting the gas pipe is formed near the center of the lid, and a gas is formed at the peripheral part of the lid. An apparatus in which a passage gap is formed has been proposed (for example, see Patent Document 1).

Japanese Patent No. 4099884

In general, in order to obtain a high-output solar cell, a high-quality polycrystalline silicon ingot is manufactured and widely used by unidirectionally solidifying a silicon melt.
However, the polycrystalline silicon ingot production apparatus described in Patent Document 1 has a low degree of freedom for optimizing crystal growth conditions, and cannot produce a high-quality polycrystalline silicon ingot. In addition, since the lid is fixed at the height of the upper opening of the crucible, there is a problem that the amount of silicon raw material charged into the crucible is limited.

  The present invention has been made in view of the above-described problems, and mainly provides a polycrystalline silicon ingot manufacturing apparatus that can manufacture a high-quality and large-sized polycrystalline silicon ingot with few SiC foreign substances. Objective.

Thus, according to the present invention, the crucible having the upper opening, the heating unit that is provided on the outer periphery of the crucible and heats and melts the silicon raw material stored in the crucible, and the crucible and the heating unit are relatively A vertical movement mechanism, a cover having an inert gas introduction hole and covering the upper opening of the crucible so as to be openable and closable, and introducing an inert gas into the inert gas introduction hole A tube, and a support member provided on an outer periphery of the crucible and supporting a lower end of the cover ,
The cover includes a peripheral wall upper end above the said upper opening edge is positioned along the upper opening edge of the crucible, detachably mounted on said peripheral wall and having an inert gas inlet, and than said upper opening edge and a lid you position the lower end upward, the polycrystalline silicon ingot production apparatus is provided.

  Further, according to another aspect of the present invention, there is provided a polycrystalline silicon ingot manufacturing method in which a polycrystalline silicon ingot is grown while introducing an inert gas using the above-described polycrystalline silicon ingot manufacturing apparatus.

According to still another aspect of the present invention, a polycrystalline silicon material manufacturing method and a polycrystalline silicon material manufacturing method for obtaining a polycrystalline silicon material by processing the polycrystalline silicon ingot manufactured by the polycrystalline silicon ingot manufacturing method. A polycrystalline silicon solar cell manufacturing method for manufacturing a polycrystalline silicon solar cell with a polycrystalline silicon material manufactured using the method is provided.
Here, in this specification, the concept including “silicon block” and “silicon wafer” is referred to as “silicon material”. Thus, for example, what is described as “polycrystalline silicon material” is meant to include “polycrystalline silicon block” and “polycrystalline silicon wafer”.

According to the polycrystalline silicon ingot producing apparatus of the present invention, it is possible to produce a polycrystalline silicon ingot with few SiC foreign substances at low cost. As a result, it is possible to reduce the cost of silicon materials and solar cells manufactured from polycrystalline silicon ingots, and the spread of polycrystalline silicon solar cells can be accelerated.
Further, by supporting the cover with the support member, it is possible to avoid the problem that when the cover is installed in the crucible, the deformation of the crucible is promoted by the weight of the cover. In this case, the material of the support member is not particularly limited as long as it is a material excellent in heat resistance and strength, and the same material as that of the crucible can be used. Further, the support member may be an outer crucible that houses the crucible.
In addition, by configuring the cover as described above, the lid can be removed from the peripheral wall, and the silicon raw material can be easily loaded into the crucible up to a position higher than the upper opening of the crucible, and the silicon raw material loading amount Can be increased. Furthermore, in this state, the upper opening of the peripheral wall is covered with a lid, the silicon raw material is melted while introducing an inert gas into the crucible, and the molten silicon melt is unidirectionally solidified to produce a polycrystalline silicon ingot. Therefore, it is possible to obtain a high-quality and large-sized polycrystalline silicon ingot in which almost no SiC foreign matter is mixed.
As a result, the cost per unit weight of a high-quality polycrystalline silicon ingot can be reduced, so that a polycrystalline silicon material obtained by processing a polycrystalline silicon ingot (obtained by processing a polycrystalline silicon ingot). Polycrystalline silicon block and polycrystalline silicon wafer obtained by processing the polycrystalline silicon in block), polycrystalline silicon solar cell manufactured using the polycrystalline silicon material (using the polycrystalline silicon material) The manufactured polycrystalline silicon solar battery cell and the polycrystalline silicon solar battery module manufactured using the polycrystalline silicon solar battery cell) can be manufactured at low cost while maintaining high quality.

It is sectional drawing which shows the time of the raw material fusion | melting in Embodiment 1 of the polycrystalline-silicon ingot manufacturing apparatus of this invention. It is sectional drawing which shows the time of completion of solidification in the polycrystalline silicon ingot manufacturing apparatus of Embodiment 1. FIG. 3 is a perspective view showing a crucible in the polycrystalline silicon ingot manufacturing apparatus of Embodiment 1. It is a front view which shows the 1st board | plate material of the cover in the polycrystalline silicon ingot manufacturing apparatus of Embodiment 1. FIG. It is a front view which shows the 2nd board | plate material of the cover in the polycrystalline silicon ingot manufacturing apparatus of Embodiment 1. FIG. It is a perspective view which shows the cover body of the cover in the polycrystalline silicon ingot manufacturing apparatus of Embodiment 1. FIG. FIG. 3 is a perspective view showing a part of a cover and an inert gas introduction pipe in the polycrystalline silicon ingot manufacturing apparatus of the first embodiment. It is a partial expanded sectional view which shows the inert gas introducing | transducing part in Embodiment 2 of the polycrystalline-silicon ingot manufacturing apparatus of this invention. It is a cross-sectional view showing the time material melting definitive to the third embodiment of the polycrystalline silicon ingot production apparatus of the present invention. It is sectional drawing which shows the time of the completion of solidification in the polycrystalline silicon ingot manufacturing apparatus of Embodiment 3. 1 is a first diagram illustrating a solar cell forming step in Example 1. FIG. FIG. 3 is a second diagram showing a solar battery cell forming step in Example 1. FIG. 5 is a third diagram illustrating a solar cell formation step in Example 1. FIG. 6 is a fourth diagram showing a solar cell formation step in Example 1. FIG. 10 is a fifth diagram illustrating a solar cell formation step in Example 1; FIG. 10 is a sixth diagram illustrating a solar cell formation step in Example 1. FIG. 10 is a seventh diagram illustrating a solar battery cell formation step in Example 1; It is an 8th figure which shows the photovoltaic cell formation process in Example 1. FIG. FIG. 10 is a ninth diagram illustrating the solar cell formation step in Example 1. 2 is a partial cross-sectional view showing a polycrystalline silicon solar cell module manufactured in Example 1. FIG.

The polycrystalline silicon ingot manufacturing apparatus of the present invention includes a crucible having an upper opening, a heating unit that is provided on the outer periphery of the crucible and heats and melts the silicon raw material housed in the crucible, the crucible and the heating unit And a cover that has an inert gas introduction hole and that covers the upper opening of the crucible so as to be openable and closable, and an inert gas that is introduced into the inert gas introduction hole. An active gas introduction pipe, and a support member provided on an outer periphery of the crucible and supporting a lower end of the cover;
The cover has a peripheral wall whose upper end is positioned above the upper opening edge along the upper opening edge of the crucible, an inert gas introduction hole, and is detachably mounted on the peripheral wall. And a lid having a lower end positioned above the edge of the upper opening,
The silicon melt is unidirectionally solidified to produce a high quality polycrystalline silicon ingot.

A generally used crucible made of graphite or quartz (SiO ₂ ) can be used as the crucible.
As the heating unit, a resistance heating type heater can be used. In addition to such a heater, a heating element made of a material having high conductivity such as graphite or carbon provided on the outer periphery of the crucible is used as the induction heating coil. The crucible may be heated by heating.

The moving mechanism may move the crucible relative to the heating unit, or may move the heating unit relative to the crucible. In addition to simplifying the structure of the polycrystalline silicon ingot manufacturing apparatus, it is preferable to employ a moving mechanism that moves the crucible with respect to the heating unit. For example, a crucible is formed by a pneumatic or hydraulic cylinder mechanism, a link mechanism, a ball screw mechanism, or the like. Can be moved up and down.
The material of the cover is not particularly limited as long as it is a material excellent in heat resistance and strength, and examples thereof include graphite, SiO ₂ , silicon carbide (SiC), etc. Among these, oxidation resistance, durability, SiC is preferable from the viewpoint of mixing impurities into Si. The cover and the inert gas introduction pipe will be described later in detail.

The polycrystalline silicon ingot manufacturing apparatus of the present invention may be configured as follows.
(1) The inert gas introduction pipe may be extendable or retractable . In this way, even if the crucible and the heating unit move relatively vertically, the ingot solidification is completed because the inert gas can be continuously introduced into the space above the crucible covered with the cover. Until then, the CO gas partial pressure in the crucible can be kept low. Further, even if the silicon raw material is charged up to a position higher than the upper opening of the crucible, the inert gas introduction tube does not get in the way.
In addition, the inert gas introduction pipe can be specifically configured as the following (2) or (3) .

(2) The inert gas introduction pipe is configured to introduce the inert gas into the first pipe into which the inert gas supplied from the inert gas supply source is introduced, and the inert gas introduction hole of the cover. It has 1 pipe | tube and the 2nd pipe | tube arrange | positioned so that an up-down direction slide is possible, and it may be comprised so that the movement of the relative up-down direction of the said crucible and the said heating part can be followed. In this case, the first tube may be slidably inserted into the second tube, and conversely, the second tube may be slidably inserted into the first tube. The material for the first and second tubes is not particularly limited as long as the material is excellent in heat resistance and strength, and examples thereof include SiC, Al ₂ O ₃ , SiO ₂ , and graphite. Of these, SiC is particularly preferable from the viewpoints of oxidation resistance, durability, and impurity incorporation into Si.

(3) A part or all of the inert gas introduction pipe may be a flexible pipe, and may be configured to be able to follow the relative vertical movement of the crucible and the heating unit.

(4) The peripheral wall may be configured such that the inner surface thereof is disposed on the inner side of the inner surface of the upper opening edge of the crucible. In this way, even if the silicon melt adheres to the peripheral wall, it flows down into the crucible. In addition, it is possible to prevent the silicon raw material from collapsing and the silicon melt from splashing out of the crucible when the silicon raw material is melted in the crucible. It will not decrease.

(5) The upper opening edge of the crucible may be square. In this case, the peripheral wall of the cover has a pair of first plates that rise along two opposing sides of the quadrangular upper opening edge of the crucible, and the other opposing ones of the quadrangular upper opening edge of the crucible. It is composed of a pair of second plate members that rise along two sides, the pair of first plate members has upper opening-like notches on both ends in the longitudinal direction, and the pair of second plates is on both ends in the longitudinal direction. And the peripheral wall may be configured to be assembled in a lattice shape by fitting the notches of the pair of second plate members into the notches of the pair of first plate members. If it does in this way, a peripheral wall can be produced easily.

(6) The cover body of the cover member may be composed of a plurality of plate members that can be divided. If it does in this way, manufacture of a lid will become easy, and handling of a lid at the time of loading a silicon raw material in a crucible will become easy.

In the method for producing a polycrystalline silicon ingot according to the present invention, the silicon raw material may be charged up to a position higher than the upper opening of the crucible.

Hereinafter, embodiments of a polycrystalline silicon ingot manufacturing apparatus of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
  FIG. 1 is a cross-sectional view showing when the raw material is melted in the first embodiment of the polycrystalline silicon ingot production apparatus of the present invention, and FIG. 2 is a cross-sectional view showing when the solidification is completed in the polycrystalline silicon ingot production apparatus of the first embodiment. .

3 is a perspective view showing a crucible in the polycrystalline silicon ingot manufacturing apparatus of the first embodiment, and FIG. 4A is a front view showing a first plate member of a cover in the polycrystalline silicon ingot manufacturing apparatus of the first embodiment. FIG. 4B is a front view showing a second plate member of the cover in the polycrystalline silicon ingot manufacturing apparatus of the first embodiment.

5 is a perspective view showing a cover body in the polycrystalline silicon ingot manufacturing apparatus of the first embodiment, and FIG. 6 shows one of the cover and the inert gas introduction pipe in the polycrystalline silicon ingot manufacturing apparatus of the first embodiment. It is a perspective view which shows a part.

(Polycrystalline silicon ingot production equipment)
This polycrystalline silicon ingot manufacturing apparatus F1 is provided in the crucible 1 provided on the outer periphery of the crucible 1 having an upper opening, the outer crucible 2 having an upper opening for accommodating the crucible 1, and the crucible 1 and the outer crucible 2. A heater (heating unit) 3 that heats and melts the contained silicon raw material Ms, a hydraulic cylinder mechanism (moving mechanism) 4 that raises and lowers the crucible 1 and the outer crucible 2 relative to the heater 3, and an inert gas introduction hole 5Ba. ₁ and a cover 5 that covers the upper opening of the crucible 1 so as to be openable and closable, and an inert gas introduction pipe 6 that introduces an inert gas into the inert gas introduction hole 5Ba ₁ , and at least the crucible 1 and the outer crucible 2 The heater 3 is housed in a heat insulating case 7. These are installed in a chamber (not shown) that can be hermetically sealed and evacuated.

  The crucible 1 is formed in a cubic shape having an upper opening 1a (see FIG. 3). Further, the outer crucible 2 is formed in a cubic shape having a size larger than that of the crucible 1. When the crucible 1 is housed in the outer crucible 2, the height of the upper opening edge 2 b of the outer crucible 2 is slightly higher than the height of the upper opening edge 1 b of the crucible 1.

Cylinder mechanism 4 includes a hydraulic cylinder body 4a having a rod 4a _1, and a lifting table 4b which is connected to the distal end of the rod 4a ₁ (upper), the outer crucible 2 is placed accommodating the crucible 1 onto the lifting table 4b Has been. A recess 4b ₁ is provided at the lower end of the lift 4b so that the lowered lift 4b does not collide with the hydraulic cylinder body 4a (see FIG. 2).

The heat insulating case 7 is made of, for example, a carbon-based heat insulating material and is supported above the hydraulic cylinder body 4a in the chamber by a support member (not shown). In the heat insulating case 7, a hole 7 a through which the lifting platform 4 b is inserted and an inert gas exhaust port 7 b are formed in the bottom wall at the lower end. Note that the inert gas exhaust port 7b may be omitted, and the exhaust gas may be exhausted from the gap of the hole 7a.
In the case of Embodiment 1, the upper part of the heat insulation case 7 is a cylindrical space portion 7c in which a second pipe 6b of an inert gas introduction pipe 6 to be described later can be moved up and down. Needless to say, the heat insulating case 7 and the chamber are provided with doors for loading the silicon raw material Ms into the crucible 1 and taking out the polycrystalline silicon ingot Mi manufactured from the crucible 1.

  Although not shown, a thermocouple is disposed in the vicinity of the center of the upper surface of the lifting platform 4b in order to detect the temperature of the silicon raw material Ms in the crucible 1. The lifting platform 4 b includes a position detector that detects the vertical position of the crucible 1. In addition, a control thermocouple is disposed to detect the temperature of the heater 3. The outputs of these thermocouples and position detectors are input to a control device (not shown), whereby the heating state by the heater 3 is controlled.

Cover 5 includes a peripheral wall 5A which rises along the upper opening edge 1b of the crucible 1, and a lid 5B releasably attached to on the peripheral wall 5A which has the inert gas introduction hole 5Ba _1.
More specifically, as shown in FIGS. 4A, 4B, and 6, the peripheral wall 5A of the cover 5 extends along two opposing sides of the square upper opening edge 1b of the crucible 1. It consists of a pair of first plate members 5Aa that rises and a pair of second plate members 5Ab that rises along the other two opposite sides of the square upper opening edge 1b of the crucible 1. In addition, 1st and 2nd board | plate material 5Aa and 5Ab are the members which formed the notch mentioned later in the rectangular board material of the same size.

The first plate member 5Aa The pair of the longitudinal ends on the side edge which has a notch 5Aa ₁ of the upper opening shape, and has a notch 5Aa ₂ rectangles the lower edge of the longitudinal ends. The notch 5Aa ₁ is formed from the upper edge of the first plate 5Aa to the middle position in the width direction (perpendicular to the longitudinal direction), and the notch 5Aa ₂ is predetermined in the width direction from the lower edge of the first plate 5Aa. It is formed by the dimension L _1. The predetermined dimension L ₁ is larger than the difference between the height of the upper opening edge 2 b of the outer crucible 2 and the height of the upper opening edge 1 b of the crucible 1 in a state where the crucible 1 is housed in the outer crucible 2. Small dimensions.

On the other hand, the pair of second plate members 5Ab has a notch 5Ab ₁ having a downward opening at the lower edge on both ends in the longitudinal direction, and a rectangular notch 5Ab ₂ on the lower edge at both ends in the longitudinal direction. . The notch 5Ab ₁ is formed from the lower edge of the second plate member 5Ab to an intermediate position in the width direction, and the notch 5Ab ₂ is formed with a predetermined dimension L ₂ in the width direction from the lower edge of the second plate member 5Ab. . The predetermined dimension L ₂ is the same as the dimension L ₁ with the notch 5Aa ₂ of the first plate member 5Aa.

Wall 5A can be assembled in a lattice pattern by fitting the 5Ab _1-out each notch of the pair of second plate members 5Ab to 5Aa _1-out each notch of the pair of first plate 5Aa, square frame portion of the peripheral wall 5A is substantially It is a natural part.
The peripheral wall 5 </ b> A configured in this way is installed on the upper opening edge 1 b of the outer crucible 2 that houses the crucible 1. At this time, the rectangular cutouts 5Aa ₂ and 5Ab ₂ (a total of 8 places) of the peripheral wall 5A are placed on the upper opening edge 1b of the outer crucible 2.

The peripheral wall 5 </ b> A is supported by the outer crucible 2, so that the peripheral wall 5 </ b> A floats from the crucible 1. Thereby, a gap is formed between the crucible 1 and the peripheral wall 5A. Further, the inner surface 5Af of the peripheral wall 5A is disposed on the inner side of the inner surface 1f of the upper opening edge 1b of the crucible 1.
Therefore, the lengths of the first and second plate members 5Aa and 5Ab of the peripheral wall 5A, the formation positions and dimensions of the notches 5Aa ₁ , 5Aa ₂ , 5Ab ₁ , and 5Ab ₂ are determined so as to obtain such an installation state. do it.
The square frame portion of the peripheral wall 5 </ b> A is a storage space for the silicon raw material Ms loaded up to a position higher than the upper opening 1 a of the crucible 1. The silicon raw material Ms can be loaded into the crucible 1 to such an extent that the silicon melt in which the silicon raw material Ms is completely dissolved in the crucible 1 does not overflow from the crucible 1. Therefore, the volume of the accommodation space of the peripheral wall 5A, that is, the height H of the peripheral wall 5A may be determined in consideration of the loading amount of the silicon raw material Ms. However, at the same time, it is necessary to consider the restrictions on the apparatus (the size of the inside of the chamber, the amount of crucible lowering during ingot unidirectional solidification, etc.).

As shown in FIGS. 5 and 6, the cover 5 </ b> B of the cover member 5 is composed of three rectangular plate members 5 </ b> Ba, 5 </ b> Bb, 5 </ b> Bc that can be divided. By arranging the long sides of these three plate members 5Ba, 5Bb, 5Bc adjacent to each other on the peripheral wall 5A, a square lid body 5B larger than the peripheral wall 5A (square frame portion) is formed. The inert gas introduction hole 5Ba ₁ is formed at the center position of the middle plate member 5Ba.

As shown in FIGS. 1, 2, and 6, the inert gas introduction pipe 6 includes a first pipe 6 a into which an inert gas supplied from an inert gas supply source (not shown) is introduced, and a cover 5. has a first pipe 6a to introduce an inert gas into the inert gas introduction hole 5Ba ₁ and vertically slidably connected to the second pipe 6b, the movement of the relative vertical direction between the crucible 1 and the heater 3 It has a double pipe structure that can be expanded and contracted so that it can follow.

In the case of the first embodiment, the first pipe 6 a passes through the upper part of the chamber and the upper part of the heat insulating case 7 and is arranged in the vertical direction, and its tip (lower end) is located near the height of the heater 3.
The second tube 6 b is a tube having an inner diameter into which the first tube 6 a can be inserted, and is placed on the lid 5 </ b> B of the cover 5. In the case of Embodiment 1, the outer flange 6b ₁ is provided at the lower end of the second pipe 6b so that the second pipe 6b is stabilized on the lid 5B. Although the outer flange 6b ₁ may be omitted, by providing the outer flange 6b ₁ at the lower end of the second pipe 6b, the lower end opening of the second pipe 6b is made an inert gas of the lid 5B (plate material 5Ba). easily positioned to the position of the introduction hole 5Ba _1. In this case, for example, a recess having a shape matching the outer shape of the outer flange 6b ₁ is formed on the upper surface of the lid 5B.

Furthermore, the polycrystalline silicon ingot manufacturing apparatus F1 of Embodiment ₁ is configured as follows in order to always arrange the inert gas introduction hole 5Ba ₁ of the lid 5B on the axial center of the first pipe 6a. It is configured. That is, a notch into which the outer peripheral portion of the lid 5B fits tightly is formed at the lattice-like upper edge of the peripheral wall 5A of the cover 5. Further, the outer crucible 2 is installed in a manner to be fitted into the lifting platform 4b. In addition, the crucible 1 is installed at substantially the same position in the outer crucible 2. With this configuration, the new crucible 1 and the outer crucible 2 are used every time the ingot is manufactured, the peripheral wall 5A of the cover 5 is set on the outer crucible 2, and the lid 5B is placed on the peripheral wall 5A after the raw materials are charged. Even when placed, the inert gas introduction hole 5Ba ₁ of the lid 5B is always arranged on the axis of the first tube 6a.

(Polycrystalline silicon ingot manufacturing method)
In the polycrystalline silicon ingot manufacturing method using the polycrystalline silicon ingot manufacturing apparatus F1 of Embodiment 1 configured as described above, first, the silicon raw material Ms is loaded into the crucible 1 outside the manufacturing apparatus F1. At this time, the crucible 1 is installed in the outer crucible 2, the peripheral wall 5 </ b> A of the cover 5 is installed on the outer crucible 2, and then the silicon raw material Ms is charged into the crucible 1. And the cover body 5B is installed on 5 A of surrounding walls, and the outer crucible 2 is installed on the raising / lowering stand 4b in a descent | fall position (refer FIG. 2).

  Then, the 2nd pipe | tube 6b is dropped and mounted on the cover body 5B, and a chamber is sealed. And the crucible 1 is raised to a manufacture start position with the cylinder mechanism 4 (refer FIG. 1). Next, the inside of the chamber is evacuated (evacuated), and an inert gas is introduced into the chamber to perform gas replacement. At this time, the inert gas introduced into the cover 5 from the first pipe 6a of the inert gas introduction pipe 6 flows out of the cover 5 through the gap between the cover 5 and the crucible 1, and enters the heat insulating case 7 and the chamber. It is filled and discharged to the outside from the inert gas exhaust port 7b.

Thereafter, while introducing an inert gas into the cover 5, the heater 3 heats the crucible 1 through the outer crucible 2 and the cover 5, thereby heating and melting the silicon raw material Ms. After confirming that all of the silicon raw material Ms has been melted, the crucible 1 is slowly lowered by the cylinder mechanism 4 at a constant speed (for example, about 30 mm / hour). Start directional solidification. At this time, since the second pipe 6b slides downward with respect to the first pipe 6a, the inert gas introduction pipe 6 gradually extends to introduce the inert gas into the cover 5.
Then, the crucible 1 is lowered to the lowest position (see FIG. 2), the completion of solidification is confirmed, an annealing process is performed after raising the crucible 1, and then the crucible 1 is taken out from the chamber by the ingot taking-out process. The polycrystalline silicon ingot Mi manufactured from is taken out.

(Polycrystalline silicon block)
The polycrystalline silicon block of the present invention can be obtained by processing the polycrystalline silicon ingot of the present invention into a desired size.
The polycrystalline silicon block can be obtained, for example, by cutting a surface portion where impurities such as a crucible material may be diffused in the polycrystalline silicon ingot of the present invention using a known apparatus such as a band saw. it can.
Moreover, you may grind | polish the surface of a polycrystalline silicon block as needed.

(Polycrystalline silicon wafer)
The polycrystalline silicon wafer of the present invention can be obtained by processing the polycrystalline silicon block of the present invention.
The polycrystalline silicon wafer can be obtained, for example, by slicing the polycrystalline silicon block of the present invention to a desired thickness using a known apparatus such as a multi-wire saw. Currently, it is often processed to a thickness of 170 μm to 200 μm.
Further, if necessary, the surface of the polycrystalline silicon wafer may be polished.

(Polycrystalline silicon solar cells)
The polycrystalline silicon solar battery cell of the present invention is manufactured using the polycrystalline silicon wafer of the present invention.
A polycrystalline silicon solar cell can be manufactured, for example, by a known solar cell process using the polycrystalline silicon wafer of the present invention. That is, in the case of a silicon wafer doped with a p-type impurity by a known method using a known material, an n-type impurity is doped to form an n-type layer to form a pn junction, and the surface electrode And a back surface electrode is formed and a polycrystalline silicon solar cell is obtained.

(Polycrystalline silicon solar cell module)
The polycrystalline silicon solar cell module of the present invention is formed by electrically connecting a plurality of polycrystalline silicon solar cells of the present invention.
For example, the polycrystalline silicon solar battery module uses the polycrystalline silicon solar battery cell of the present invention to electrically connect a plurality of solar battery cells with an interconnector (conductive member) by a known solar battery module process. And it can be manufactured by sealing it.

(Embodiment 2)
FIG. 7 is a partially enlarged cross-sectional view showing an inert gas introducing portion in Embodiment 2 of the polycrystalline silicon ingot manufacturing apparatus of the present invention.
The second embodiment is different from the first embodiment only in the configuration of the inert gas introduction pipe, and the other configurations in the second embodiment are the same as those in the first embodiment. Therefore, only different points will be described below.

  The inert gas introduction pipe 16 in the polycrystalline silicon ingot manufacturing apparatus according to the second embodiment includes a first pipe 16a into which an inert gas supplied from an inert gas supply source (not shown) is introduced, and an inert gas introduction to the cover. It has the 1st pipe | tube 16a and the 2nd pipe | tube 16b connected so that an up-down direction sliding was possible so that an inert gas may be introduce | transduced into a hole, and the 2nd pipe | tube 16b is slidably inserted in the 1st pipe | tube 16a. In this way, the inert gas introduction pipe 16 may have a double pipe structure that can be expanded and contracted.

(Embodiment 3)
FIG. 8 is a cross-sectional view showing the start of production in the third embodiment of the polycrystalline silicon ingot production apparatus of the present invention, and FIG. 9 is a cross-sectional view showing the end of production in the polycrystalline silicon ingot production apparatus of the third embodiment. . In FIGS. 8 and 9, the same elements as those in FIGS. 1 and 2 are denoted by the same reference numerals. 8 and 9, the silicon raw material and the manufactured polycrystalline silicon ingot are not shown.

  In the polycrystalline silicon ingot manufacturing apparatus F3 of Embodiment 3, a part or all of the inert gas introduction pipe 26 is formed of a flexible pipe and is configured to be able to follow the relative vertical movement of the crucible 1 and the heater 3. ing. In this case, the upper part of the heat insulation case 27 is a space in which the inert gas introduction pipe 26 can be bent.

Furthermore, in the case of the third embodiment, for example, at the distal end of the inert gas introduction pipe 26, the distal end of the flexible inert gas introduction pipe 26 does not deviate from the inert gas introduction hole 5Ba ₁ of the lid 5B of the cover 5. A connecting pipe 27 is inserted. The connecting pipe 27 has an outer flange 27a at the lower end, and as described above, the outer flange 27a is positioned in a recess formed on the upper surface of the lid 5B.
Or you may employ | adopt the following retaining structures. In this case, for example, one or more protrusions are provided on the inner peripheral surface of the inert gas introduction hole 5Ba ₁ of the lid 5B. Further, a connecting pipe not having the outer flange 27a is inserted into the distal end of the flexible inert gas introduction pipe 26, and an inverted L-shaped groove for inserting the protrusion is formed on the outer peripheral surface of the connecting pipe. To do. In this way, when the tip of the connection pipe is inserted into the inert gas introduction hole 5Ba ₁ , the protrusion is inserted into the groove, and if the connection pipe is turned a little, the protrusion enters the depth of the groove. The active gas introduction pipe 26 is prevented from coming off from the inert gas introduction hole 5Ba ₁ .
Other configurations in the third embodiment are substantially the same as those in the first and second embodiments.

(Other embodiments)
1. In the first embodiment (FIGS. 1 and 2) and the third embodiment (FIGS. 8 and 9), the hydraulic cylinder mechanism is exemplified as the moving mechanism. However, for example, a ball screw mechanism may be employed. In this case, it is preferable that the rotation shaft of the ball screw mechanism is not inserted into the heat insulating cover.

2. The height of the upper opening edge 1 b of the crucible 1 may be slightly higher than the height of the upper opening edge 2 b of the outer crucible 2. In this case, instead of the first and second plate members 5Aa and 5Ab (see FIGS. 4A and 4B) constituting the peripheral wall of the cover, notches in the first and second plate members 5Aa and 5Ab are provided. This can be dealt with by forming the peripheral wall using the first and second plate members having the protruding pieces projecting 5Aa ₂ and 5Ab ₂ downward from the lower edge by dimensions L ₁ and L ₂ .

3. The inert gas introduction pipe 6 does not necessarily have a double structure. In a limited apparatus, in order to increase the loading amount of the silicon raw material as much as possible, it is necessary to attach a cover having a high height. For this purpose, it is preferable to use a triple or more multiple structure. However, since the structure becomes complicated, for example, troubles such as SiO powder generated from the silicon melt accumulate in the movable part and become unable to move can be considered, which involves a risk.
The inert gas introduction pipe 6 can be a single pipe. However, in order to increase the loading amount of the silicon raw material, depending on the shape of the apparatus, it is necessary to take measures such as melting silicon with the crucible position lowered. In this case, since the melted silicon melt flows down to the bottom of the crucible having a low temperature, there is a risk of crucible cracking. Further, since the silicon melted at the upper part of the raw material silicon may come into contact with the inert gas introduction pipe 6 and contaminate the raw material, the inert gas introduction pipe 6 is preferably double or more.

Example 1
<Manufacture of polycrystalline silicon ingot>
In Example 1, first, a p-type polycrystalline silicon ingot was manufactured using the polycrystalline silicon ingot manufacturing apparatus F1 of Embodiment 1 described with reference to FIGS.
At this time, a crucible 1 having an internal volume of 830 mm in length, 830 mm in width, and 420 mm in height was used.
Further, in the used cover 5, the distance from the upper opening edge 1b of the crucible 1 to the lower surface of the lid 5B is 200 mm, and the distance between the first plate members 5Aa facing each other and the distance between the second plate members 5Ab facing each other. Was 815 mm, and the plate thickness of the lid 5B was 15 mm.
Moreover, as the 2nd pipe | tube 6b of the inert gas introduction pipe | tube 6, the thing of length 180mm was used.
The outer crucible 2 was 15 mm higher than the upper opening edge 1b of the crucible 1 in the outer crucible 2.

Next, the crucible 1, the cover 5 and the like were all set at predetermined positions in the apparatus, and then the silicon raw material Ms was loaded into the crucible 1. In order to reduce the cost of the polycrystalline silicon ingot, it is desirable to put as much silicon raw material Ms as possible into the crucible 1. Therefore, when the silicon raw material Ms was charged as much as possible, the loading amount was 565 kg.
Next, the chamber door was closed, the crucible 1 was raised to the initial position shown in FIG. 1, evacuation was performed, and the silicon raw material Ms was heated to 800 ° C. by the heater 3. Then, while introducing argon gas from the inert gas introduction pipe 6 at a flow rate of 40 L / min, the mixture was heated to 1550 ° C. and waited until all of the silicon raw material Ms was melted. Next, it hold | maintained for 30 minutes by melting | fusing point +15 degreeC of silicon | silicone, Then, temperature control and crucible position control were performed according to the predetermined | prescribed recipe.

At the start of silicon melting, the tip of the first tube 6a of the inert gas introduction tube 6 is inserted into the cover 5 up to a position 10 mm from the lower surface of the lid 5B, and the crucible 1 is maximized from the initial position during unidirectional solidification. It was lowered 200 mm. Therefore, in Example 1, the state where the first pipe 6a of the inert gas introduction pipe 6 was inserted into the second pipe 6b was maintained until the solidification of the upper surface of the ingot was completed.
After confirming that solidification was completed up to the upper surface of the ingot from the output tendency of the heater 3, annealing was performed at 1200 ° C. for 2 hours, cooled, and the ingot was taken out.
When the upper surface of the ingot was visually confirmed, the ingot of Example 1 showed a metallic luster on the entire surface.

<Block processing>
Next, the crucible 1 was broken, the polycrystalline silicon ingot Mi was taken out, the bottom of the ingot was fixed with a bond, and 25 156 mm square blocks were cut out with a band saw. Subsequently, the end portions of the blocks corresponding to the upper and lower portions of the ingot were each cut by about 15 mm. Thereafter, the side surfaces of each block were polished. When SiC foreign material is seen on the side surface of the block, the wire saw may be disconnected in the subsequent slicing step, so that the block foreign material is defective, and the results are shown in Table 1. In Table 1, the numerical values of Example 1 and Example 2 described later are ratios (%) when the result of Comparative Example 1 described later is 100.

<Slicing>
Next, the polycrystalline silicon block obtained by the block processing was sliced to a thickness of 180 μm with a wire saw. After processing, the surface was washed to remove dirt and visually inspected. A wafer in which a step defect considered to be caused by a SiC foreign material and a foreign material were confirmed was regarded as a wafer foreign material defect, and the results are shown in Table 1.

<Solar cell formation process>
Next, the polycrystalline silicon wafer obtained by the slicing process was put into the following solar cell forming process.
First, as shown in FIG. 10 (A), a p-type polycrystalline silicon wafer 11 having a thickness of about 170 μm is prepared. As shown in FIG. 10 (B), PSG (phosphorus silicate) is formed on the surface of the polycrystalline silicon wafer 11. Glass) liquid 41 was applied.

  Next, phosphorus was diffused from the PSG liquid 41 to the polycrystalline silicon wafer 11 by heating the polycrystalline silicon wafer 11 after the application of the PSG liquid 41. Thus, as shown in FIG. 10C, an n + layer 42 having a thickness of 0.3 μm was formed on the surface of the polycrystalline silicon wafer 11 on the light receiving surface side. At this time, a PSG film 41 a having a thickness of about 1 μm was formed on the n + layer 42. Thereafter, as shown in FIG. 10D, the PSG film 41a formed during the diffusion of phosphorus was removed.

Next, as shown in FIG. 10E, an antireflection film 43 made of a silicon nitride film was formed on the n + layer 42 of the polycrystalline silicon wafer 11 to a thickness of 0.08 μm.
Next, as shown in FIG. 10F, an aluminum paste 44a was applied to the back surface (non-light-receiving surface) of the polycrystalline silicon wafer 11. Then, the polycrystalline silicon wafer 11 after the application of the aluminum paste 44a is baked at 770 ° C. to diffuse aluminum from the aluminum paste 44a to the back surface of the polycrystalline silicon wafer 11, and as shown in FIG. The aluminum electrode 44 and the p + layer 45 were simultaneously formed on the back surface of the polycrystalline silicon wafer 11.

  Next, as shown in FIG. 10H, a silver paste 46a is applied on the surface of the antireflection film 43, and a silver paste 47a is applied on the back surface of the polycrystalline silicon wafer 11, and then fired at 700 ° C. did. As a result, as shown in FIG. 10 (I), a silver electrode 46 as a front electrode electrically connected to the n + layer 42 is formed, and a silver electrode electrically connected to the back surface of the polycrystalline silicon wafer 11. 47 was formed, and a polycrystalline silicon solar battery cell 40 was manufactured.

  Thereafter, characteristic inspection was performed in the final process. In the characteristic inspection, under the solar simulator, IV measurement in a state where light irradiation was performed and reverse direction IV measurement in a state where light was not irradiated were performed. In particular, when SiC foreign matter is present in the surface of the polycrystalline silicon wafer, there is a concern about leakage failure (hereinafter referred to as Id failure) in a state where light is not irradiated. This is presumably because the SiC foreign matter generally contains nitrogen impurities, which are n-type dopants, and thus is a low-resistance n-type foreign matter. Table 1 shows the Id defect rate results for Example 1.

<Solar cell modularization process>
The polycrystalline silicon solar battery module 50 shown in FIG. 11 was manufactured by electrically connecting a plurality of polycrystalline silicon solar battery cells 40 of Example 1 in series.
That is, the silver electrode 46 which is a surface electrode on the light receiving surface side of one polycrystalline silicon solar cell 40 and the silver electrode 47 on the back surface side of the other polycrystalline silicon solar cell 40 which are arranged adjacent to each other. Were electrically connected by a conductive member 51 called an interconnector. Thereby, a solar cell string in which these polycrystalline silicon solar cells 40 were electrically connected in series was manufactured.

  And the said solar cell string was sealed in the sealing material 54 installed between the transparent substrate 52 and the protective sheet 53, and the polycrystalline-silicon solar cell module was manufactured. Here, a glass substrate was used as the transparent substrate 52. Further, a PET (polyethylene terephthalate) film was used as the protective sheet 53. Further, EVA (ethylene vinyl acetate) was used as the sealing material 54.

(Example 2)
In Example 2, a polycrystalline silicon ingot was manufactured in the same manner as in Example 1 except that the length of the second pipe 6b of the inert gas introduction pipe 6 was 130 mm.
The length of the second pipe 6b of the inert gas introduction pipe 6 used in the second embodiment is shorter than the length of the second pipe 6b of the inert gas introduction pipe 6 used in the first embodiment. When the crucible 1 was lowered by a maximum of 200 mm, the tip (lower end) of the first tube 6a and the upper end of the second tube 6b were separated by 45 mm. That is, the first pipe 6a is in a state of being removed from the second pipe 6b.

Using the polycrystalline silicon ingot of Example 2, block processing and polishing were performed in the same manner as in Example 1. Further, in Example 2, similarly to Example 1, determination was made regarding block foreign body defects on the side surfaces of the blocks, and the results are shown in Table 1.
Next, the block of Example 2 was sliced and washed in the same manner as in Example 1, and the wafer foreign matter failure was determined by visual inspection. The results are shown in Table 1.
Using the wafer of Example 2, a polycrystalline silicon solar cell was formed in the same manner as in Example 1, and Id defect inspection was performed. The results are shown in Table 1.
Thereafter, using the solar battery cell of Example 2, a polycrystalline silicon solar battery module was produced in the same manner as in Example 1.

(Comparative Example 1)
As Comparative Example 1, a polycrystalline silicon ingot was manufactured in the same manner as in Example 1 except that a polycrystalline silicon ingot manufacturing apparatus without the cover 5 and the second tube 6b was used.
In Comparative Example 1, the loading amount of the silicon raw material Ms into the crucible 1 was 450 kg.
When the upper surface of the ingot of Comparative Example 1 was visually confirmed, cloudiness was observed, and a green foreign substance thought to be SiC was found on a part of the upper surface.

Using the polycrystalline silicon ingot of Comparative Example 1, block processing and polishing were performed in the same manner as in Example 1. Further, in Comparative Example 1 as well as in Example 1, determination was made regarding block foreign body defects on the side surfaces of the blocks, and the results are shown in Table 1.
Next, the block of Comparative Example 1 was sliced and washed in the same manner as in Example 1, and the wafer foreign matter failure was determined by visual observation. The results are shown in Table 1.
Using the wafer of Comparative Example 1, a polycrystalline silicon solar battery cell was subjected to Id defect inspection in the same manner as in Example 1, and the results are shown in Table 1.
Thereafter, using the solar battery cell of Comparative Example 1, a polycrystalline silicon solar battery module was produced in the same manner as in Example 1.

From the results of Table 1, it was confirmed that Examples 1 and 2 had better results with respect to block foreign matter, wafer foreign matter and Id defect than Comparative Example 1, and that Example 1 was particularly good.
In addition, regarding the production of a polycrystalline silicon solar battery module using the polycrystalline silicon solar battery cells of Examples 1 and 2 and Comparative Example 1, there is no significant difference in characteristics and yield. Since there is a difference in the loading amount of the silicon raw material, and a difference due to SiC foreign matter is seen in the block yield, the slice yield, and the solar cell inspection yield, the cost of the module is shown in Example 1 <Example 2 << Comparison Example 1 was obtained. Therefore, the present invention makes it possible to supply a polycrystalline solar cell module to the market at a low price.

  The embodiments and examples herein are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Crucible 1a Upper opening 1b Upper opening edge 1f Inner surface of upper opening edge of crucible 2 Outer crucible (support member)
3 Heater (heating part)
4 Cylinder mechanism (moving mechanism)
5 Cover 5A wall 5Af wall of the inner surface 5Aa first plate 5Ab second plate 5Aa _1, 5Aa _2, 5Ab _1, 5Ab _2, the notch 5B lid 5Ba, 5Bb, 5Bc plate 5Ba ₁ inert gas inlet 6 and 16, 26 Inert gas introduction pipe 6a, 16a First pipe 6b, 16b Second pipe 40 Polycrystalline silicon solar cell (solar cell)
50 polycrystalline silicon solar cell module F1, F2 polycrystalline silicon ingot manufacturing equipment Mi polycrystalline silicon ingot Ms silicon raw material

Claims (14)

  A crucible having an upper opening, a heating unit that is provided on the outer periphery of the crucible and heats and melts the silicon raw material housed in the crucible, and a movement that moves the crucible and the heating unit relatively in the vertical direction A mechanism, a cover having an inert gas introduction hole and covering the upper opening of the crucible so as to be openable and closable, and an inert gas introduction pipe for introducing an inert gas into the inert gas introduction hole are provided. A polycrystalline silicon ingot manufacturing apparatus.   The polycrystalline silicon ingot manufacturing apparatus according to claim 1, wherein the inert gas introduction pipe is extendable or retractable.   The inert gas introduction pipe includes a first pipe into which an inert gas supplied from an inert gas supply source is introduced, and the first pipe to introduce an inert gas into the inert gas introduction hole of the cover. 3. The polycrystalline silicon according to claim 1, further comprising a second tube connected to be slidable in the vertical direction and configured to be able to follow relative vertical movement of the crucible and the heating unit. Ingot manufacturing equipment.   3. The polycrystal according to claim 1, wherein a part or all of the inert gas introduction pipe is formed of a flexible pipe, and is configured to be able to follow a relative vertical movement of the crucible and the heating unit. Silicon ingot manufacturing equipment.   The polycrystalline silicon ingot manufacturing apparatus according to claim 1, further comprising a support member provided on an outer periphery of the crucible and supporting a lower end of the cover.   The said cover has a peripheral wall which stands | starts up along the upper opening edge of the said crucible, and has a cover body which has an inert gas introduction hole and is detachably attached on the said peripheral wall. The polycrystalline silicon manufacturing apparatus as described in one.   The polycrystalline silicon ingot manufacturing apparatus according to claim 6, wherein an inner surface of the peripheral wall is arranged on an inner side of an inner surface of an upper opening edge of the crucible. The upper opening edge of the crucible is square,
A peripheral wall of the cover is formed on a pair of first plate members that rise along two opposing sides of the upper opening edge of the crucible quadrilateral, and on the other two sides of the crucible quadrangular upper opening edge. It consists of a pair of second plates that rise along
A pair of 1st board | plate materials have a notch of upper opening shape in the both ends side of a longitudinal direction,
A pair of 2nd board | plate materials have a notch of a downward opening shape in the both ends side of a longitudinal direction,
8. The polycrystalline silicon ingot manufacture according to claim 6, wherein the peripheral wall is configured to be assembled in a lattice shape by fitting the notches of the pair of second plate members into the notches of the pair of first plate members. apparatus.   The polycrystalline silicon ingot manufacturing apparatus according to any one of claims 6 to 8, wherein the cover body of the cover member is composed of a plurality of separable plate members.   A method for producing a polycrystalline silicon ingot, wherein the polycrystalline silicon ingot is grown while introducing an inert gas using the polycrystalline silicon ingot producing apparatus according to claim 1.   The method for producing a polycrystalline silicon ingot according to claim 10, wherein raw material silicon is charged to a position higher than an upper opening of the crucible.   A polycrystalline silicon ingot produced by the method for producing a polycrystalline silicon ingot according to claim 10.   A polycrystalline silicon material obtained by processing the polycrystalline silicon ingot according to claim 12.   A polycrystalline silicon solar cell manufactured using the polycrystalline silicon material according to claim 13.